Method to form metal matrix composite reinforced with eggshell

Abstract

A method to form a metal matrix composite reinforced with eggshell (ES). The method includes preparing an ES powder, blending and milling the ES powder with at least one metal powder selected from the group consisting of magnesium (Mg), zirconium (Zr) to form a powder mixture, compacting and sintering the powder mixture to form the metal matrix composite. In addition, a MgZr-ES metal matrix composite with improved corrosion resistance, having an amount of magnesium from 95 to 97 wt. %, an amount of zirconium from 1 to 2 wt. %, and an amount of ES from 1 to 4 wt. %, may be used for biomedical applications.

Claims

1. A method to form a metal matrix composite reinforced with eggshell(ES), comprising: blending and milling a powder consisting of at least one magnesium (Mg) powder and at least one zirconium (Zr) powder and at least one ES powder to form a powder mixture; compacting the powder mixture in a press to form a compacted powder mixture; and sintering the compacted powder mixture to form a composite matrix by making the compacted powder mixture coalesce into a solid or porous mass by heating it without complete liquifaction; wherein said at least one Mg powder has a particle size in a range of 20 to 70 micrometers (m); wherein said at least one Zr powder has a particle size in a range of 20 to 60 m; wherein after the sintering, the composite matrix consists of magnesium, zirconium, and ES; and wherein the amount of magnesium in the composite matrix is from 89.9 to 99.9 wt. %, the amount of zirconium in the composite matrix is from 0.1 to 10 wt. %, and the amount of ES in the composite matrix is from 0.1 to 10 wt. %.

2. The method of claim 1, wherein: the amount of magnesium in the composite matrix is from 95 to 97 wt. %, the amount of zirconium in the composite matrix is from 1 to 2 wt. %, and the amount of ES in the composite matrix is from 1 to 4 wt. %.

3. The method of claim 1, further comprising: heating, drying and crushing the eggshell(ES) to form a crushed ES; and grinding the crushed ES to form the ES powder, wherein the ES powder has a reduced particle size compared to the crushed ES.

4. The method of claim 3, wherein: the ES powder has an irregular size and shape; and the ES powder has an average particle size in a range of 1 to 10 m.

5. The method of claim 3, wherein: the ES powder has a peak in a range of 2 theta () value 28 to 32 in an XRD spectrum.

6. The method of claim 1, wherein: the composite matrix has a density of from 1.7 to 2.0 g/cm.sup.3.

7. The method of claim 1, wherein: the composite matrix has a microhardness of from 30 to 80 vickers pyramid number (HV).

8. The method of claim 1, wherein: Zr and ES are uniformly distributed throughout the composite matrix.

9. The method of claim 1, wherein after the sintering of the compacted powder mixture, the composite matrix has a densification of from 90 to 100%.

10. The method of claim 1, wherein after the sintering of the compacted powder mixture, the composite matrix has a densification of from 98% to 99.9%.

11. The method of claim 1, wherein the milling of the powder mixture occurs at a speed of from 175 to 225 rotations per minute (rpm); wherein the compacting of the powder mixture occurs at a pressure of from 300 to 800 megapascal (MPa); and wherein the sintering of the compacted powder mixture occurs at a temperature of from 300 to 600 degrees Celsius ( C.).

12. The method of claim 1, wherein after the sintering of the compacted powder mixture, said composite matrix has a corrosion potential (E.sub.corr) value of from 1.7 to 1.4 voltage (V).

13. The method of claim 1, wherein after the sintering of the compacted powder mixture, said composite matrix has a current density (I.sub.corr) value of from 20 to 280 microampere per square centimeter (A/cm.sup.2).

14. The method of claim 1, wherein the compacted powder mixture is a compacted Mg-1 wt % Zr-2.5 wt % ES powder mixture, and is sintered at 450 C. in an argon atmosphere.

15. The method of claim 1, wherein after the sintering of the compacted powder mixture, SEM micrographs reveal no visible porosity in the metal matrix composite.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A more complete appreciation of this disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

(2) FIG. 1 shows an XRD pattern of magnesium powder and zirconium powder, according to certain embodiments.

(3) FIG. 2 shows an XRD pattern of crushed ES and ES powder, according to certain embodiments.

(4) FIG. 3A shows an XRD pattern of sintered magnesium and sintered Mg-1Zr, according to certain embodiments.

(5) FIG. 3B shows an XRD pattern of sintered magnesium and sintered Mg-2.5ES, according to certain embodiments.

(6) FIG. 3C shows an XRD pattern of sintered magnesium and sintered Mg-1Zr-2.5ES, according to certain embodiments.

(7) FIG. 4A shows an SEM micrograph of magnesium powder, according to certain embodiments.

(8) FIG. 4B shows an SEM micrograph of zirconium powder, according to certain embodiments.

(9) FIG. 4C shows an SEM micrograph of crushed ES, according to certain embodiments.

(10) FIG. 4D shows an SEM micrograph of ES powder, according to certain embodiments.

(11) FIG. 5A shows an SEM image, and corresponding elemental map of the Mg-2.5ES powder mixture, according to certain embodiments.

(12) FIG. 5B shows an SEM image, and corresponding elemental map of the Mg-1Zr mixed powder, according to certain embodiments.

(13) FIG. 5C shows an SEM image, and corresponding elemental map of the Mg-1Zr-2.5ES powder mixture, according to certain embodiments.

(14) FIG. 6A shows an SEM micrograph of the sintered magnesium, according to certain embodiments.

(15) FIG. 6B shows an SEM micrograph of the sintered Mg-1Zr, according to certain embodiments.

(16) FIG. 6C shows an SEM micrograph of the Mg-2.5ES composite, according to certain embodiments.

(17) FIG. 6D shows an SEM micrograph of the Mg-1Zr-2.5ES composite, according to certain embodiments.

(18) FIG. 7A shows an SEM image and corresponding EDX maps of the Mg-2.5ES composite, according to certain embodiments.

(19) FIG. 7B shows an SEM image and corresponding EDX maps of the Mg-1Zr-2.5ES composite, according to certain embodiments.

(20) FIG. 8 shows OCP curves of materials in Hank's medium, according to certain embodiments.

(21) FIG. 9 shows LPR curves of materials in Hank's medium, according to certain embodiments.

(22) FIG. 10 shows PDP curves of materials in Hank's medium, according to certain embodiments.

(23) FIG. 11 shows Nyquist curves of materials in Hank's medium, according to certain embodiments.

(24) FIG. 12 shows Bode curves of materials in Hank's medium, according to certain embodiments.

DETAILED DESCRIPTION

(25) In the drawings, like reference numerals designate identical or corresponding parts throughout the several views. Further, as used herein, the words a, an and the like generally carry a meaning of one or more, unless stated otherwise.

(26) Furthermore, the terms approximately, approximate, about, and similar terms generally refer to ranges that include the identified value within a margin of 20%, 10%, or preferably 5%, and any values there between.

(27) As used herein, the term composite refers to a material formed by at least two components with significantly different physical or chemical properties, when combined, produces a material with characteristics different from the individual components, wherein one of the components is a matrix in an amount typically in a range of about 50% to about 99.9% of the total weight of the composite.

(28) As used herein, the term metal matrix refers to an interconnected or continuous network comprising at least one metal. The metal matrix may comprise a single metal, metal alloy, and/or an intermetallic.

(29) As used herein, the terms metal matrix composite, metal composite matrix, and composite matrix are used interchangeably and are intended to refer to a composite of a metal matrix.

(30) As used herein, the terms eggshell, eggshell material, ES material, and ES are used interchangeably and are intended to refer to an outer covering of a hard-shelled egg, and of some forms of eggs with soft outer coats.

(31) As used herein, the term mixture refers to a composition comprising at least two chemical constituents, such as two chemical compounds, or a chemical compound, and a chemical element. The constituents of the mixture may be more or less homogeneously distributed.

(32) As used herein, the term powder refers to a solid composed of a large number of fine particles that may flow freely when shaken or tilted. The particles may have varied morphology which include one-dimensional (fibers, tubes, and the like), two-dimensional (platelets, films, laminates, planar, and the like), and three-dimensional (spheres, cones, ovals, cylindrical, cubes, monoclinic, parallelepipeds, dumbbells, hexagonal, truncated dodecahedron, irregular shaped structures, and the like) morphology.

(33) As used herein, the term metal powder refers to powder of pure metal, alloy, intermetallic compound, and mixtures thereof. The term includes powder of metallic primary particles, aggregates, agglomerates, other discrete metal particles, or any combination thereof. Further, the term includes single metal, multi-metal, and complex compositions.

(34) As used herein, the term ES powder, and eggshell powder are used interchangeably and are intended to refer to powder of the eggshell.

(35) As used herein, the term sinter refers to making a powdered material coalesce into a solid or porous mass by heating it without complete liquefaction.

(36) As used herein, the term full density refers to a density greater than 95% of theoretical density.

(37) As used herein, the term compact refers to an intermediate product form that has not been compressed to full density. A compact may be an axisymmetric billet shape or near-net shape or any other shape advantageous to downstream processing.

(38) As used herein, the term phase refers to (as in thermodynamics) a homogeneous volume of matter.

(39) As used herein, the term heating refers to any thermal treatment at or to a desired heating temperature.

(40) As used herein, the term drying, refers to any process of removing a significant portion of water.

(41) As used herein, the term milling when used in relation to milling a plurality of particles in addition to a conventional milling machine operation, refers to any process in which particles and any optional additives are mixed to achieve a substantially uniform mixture.

(42) As used herein, the term grinding, refers to any process of reducing the size of something by crushing it.

(43) As used herein, the term compacting refers to any process of applying pressure on the mixture to obtain a preferred geometry.

(44) As used herein, the term metal refers to essentially pure metal, or a commercially available metal having impurities and/or alloying constituents therein.

(45) As used herein, the term magnesium, and Mg are used interchangeably and are intended to refer to magnesium metal.

(46) As used herein, the term zirconium, and Zr are used interchangeably and are intended to refer to zirconium metal.

(47) Aspects of the present disclosure are directed towards a method to form a metal matrix composite reinforced with an eggshell (ES), for example, a method to form a MgZr-ES metal matrix composite. The formed MgZr-ES metal matrix composite has a homogeneous distribution of reinforcement, shows enhanced microhardness and improved in vitro corrosion properties, which opens the door for exploring the green and low-cost ES reinforced materials for biomedical applications. The structure, microstructure, densification, microhardness and in vitro corrosion characteristics of the resultant MgZr-ES metal composite are also analyzed using different analytical techniques.

(48) In one embodiment, the method includes blending and milling at least one metal powder and at least one ES powder to form a powder mixture, compacting the powder mixture in a press to form a compacted powder mixture, and sintering the compacted powder mixture to form a composite matrix. In yet another embodiment, the step of forming the powder mixture comprises blending at least one metal powder and at least one ES powder to provide a blended powder and mixing the blended powder by using the milling machine.

(49) In another embodiments, the metal powder comprises at least one magnesium (Mg) powder and at least one zirconium (Zr) powder. In some embodiments, the Mg powder has a particle size in a range of 20 to 70 micrometers (m), preferably 30 to 60 m, more preferably 40 to 50 m. In some embodiments, the Zr powder has a particle size in a range of 20 to 60 micrometers (m), preferably 30 to 50 m, more preferably 40 to 50 m. Other ranges are also possible.

(50) In an exemplary embodiment, the metal composite matrix comprises magnesium and zirconium. In another exemplary embodiment, the metal composite matrix comprises magnesium and ES. In yet another exemplary embodiment, the composite matrix comprises magnesium, zirconium, and ES.

(51) In one embodiment, the metal composite matrix comprises magnesium and zirconium, wherein an amount of magnesium in the composite matrix is from 95 to 99.9 wt. %, an amount of zirconium in the composite matrix is from 0.1 to 5.0 wt. %. In another embodiment, the metal composite matrix comprises magnesium and zirconium, wherein an amount of magnesium in the composite matrix is from 97 to 99.5 wt. %, an amount of zirconium in the composite matrix is from 0.5 to 3.0 wt. %. In a further preferred embodiment, the metal composite matrix comprises magnesium and zirconium, wherein an amount of magnesium in the composite matrix is from 98.5 to 99.5 wt. %, an amount of zirconium in the composite matrix is from 0.5 to 1.5 wt. %. Other ranges are also possible.

(52) In one embodiment, the metal composite matrix comprises magnesium and ES, wherein an amount of magnesium in the composite matrix is from 90 to 99.9 wt. %, an amount of ES in the composite matrix is from 0.1 to 10 wt. %. In another embodiment, the metal composite matrix comprises magnesium and ES, wherein an amount of magnesium in the composite matrix is from 95 to 99 wt. %, an amount of ES in the composite matrix is from 1.0 to 5.0 wt. %. In a further preferred embodiment, the metal composite matrix comprises magnesium and ES, wherein an amount of magnesium in the composite matrix is from 97 to 98 wt. %, an amount of ES in the composite matrix is from 1 to 4 wt. %. Other ranges are also possible.

(53) In yet another embodiment, the composite matrix comprises magnesium, zirconium, and ES, wherein an amount of magnesium in the composite matrix is from 89.9 to 99.9 wt. %, and an amount of zirconium in the composite matrix is from 0.1 to 10 wt. %, and an amount of ES in the composite matrix is from 0.1 to 10 wt. %. In a further preferred embodiment, the composite matrix comprises magnesium, zirconium, and ES, wherein an amount of magnesium in the composite matrix is from 95 to 99 wt. %, an amount of zirconium in the composite matrix is from 0.5 to 2 wt. %, and an amount of ES in the composite matrix is from 0.5 to 5 wt. %. In a more preferred embodiment, the composite matrix comprises magnesium, zirconium, and ES, wherein an amount of magnesium in the composite matrix is from 95 to 97 wt. %, an amount of zirconium in the composite matrix is from 1 to 2 wt. %, and an amount of ES in the composite matrix is from 1 to 4 wt. %. Other ranges are also possible.

(54) In an embodiment, the method comprises a step of preparing the ES powder. In another embodiment, the step of preparing the ES powder comprises heating, drying, and crushing the eggshell to from a crushed ES. In yet another embodiment, the step of preparing the ES powder comprises grinding the crushed ES to form the ES powder, wherein the ES powder has a reduced particle size. In an exemplary embodiment, the step of preparing the ES powder comprises heating the ES material in boiling water. In yet another embodiment, the step of preparing the ES powder comprises drying the heated ES material to provide a dried ES material. In yet another embodiment, the step of preparing the ES powder comprises crushing the dried ES material to form a crushed ES. In yet another embodiment, the step of preparing the ES powder comprises grinding the crushed ES to form the ES powder.

(55) In yet another embodiment, the ES material is crushed before heating, drying, or grinding steps to provide a crushed ES material.

(56) In certain embodiments, the crushed ES has a flake-like morphology. In some embodiments, the crushed flakes have a length in a range of 1 to 500 m, preferably 5 to 300 m, more preferably 10 to 200 m, and even more preferably 10 to 100 m. In some embodiments, the crushed flakes have a width in a range of 1 to 300 m, preferably 5 to 200 m, more preferably 5 to 100 m, and even more preferably 5 to 50 m. Other ranges are also possible.

(57) In an embodiment, the ES powder has one-dimensional morphology, two-dimensional morphology, three-dimensional morphology, and any combination thereof. In another embodiment, the ES powder has one-dimensional morphology including but not limited to fibers, and tubes. In yet another embodiment, the ES powder has two-dimensional morphology including but not limited to platelets, films, laminates, planar, and flakes. In yet another embodiment, the ES powder has three-dimensional morphology including but not limited to spheres, cones, ovals, cylindrical, cubes, monoclinic, parallelepipeds, dumbbells, hexagonal, truncated dodecahedron, and irregular shaped structures. In an exemplary embodiment, the ES powder has an irregular size and shape. In certain embodiments, the ES powder has a particle size in a range of 0.1 to 100 m, preferably 0.5 to 50 m, more preferably 1 to 25 m, and even more preferably 1 to 10 m. Other ranges are also possible.

(58) In some embodiments, the crushed ES has a broad and intense peak in a range of 2 theta () value 25 to 35, 27 to 33, 29 to 31 in an X-ray diffraction (XRD) spectrumas illustrated in FIG. 2. In some embodiments, the ES powder has an intense peak in a range of 2 value 28 to 32, 29 to 31 in the XRD spectrum as illustrated in FIG. 2. The change of peak intensity and shape in the XRD spectrum as depicted in FIG. 2, indicates a decrease of ES crystallite size and particle size refinement.

(59) The density of the composite matrix is determined following ASTM B962-17 standards. The composite matrix prepared by the method disclosed provides a near-dense material. In some embodiments, the composite matrix has a density of from 1.7 to 2.0 g/cm.sup.3, preferably from 1.7 to 1.8 g/cm.sup.3. In some embodiments, the composite matrix has a densification of from 90 and 100%, preferably from 98 to 99.9%. Other ranges are also possible.

(60) Microhardness is determined using the HV test following ASTM E384-08, which measures the hardness of materials with low applied loads. In some embodiments, the composite matrix has a microhardness of from 30 to 80 vickers pyramid number (HV), preferably from 40 to 70 HV, and more preferably from 50 to 60 HV. Other ranges are possible.

(61) In an embodiment, the zirconium and ES particles are uniformly distributed throughout the composite matrix.

(62) The method to form the metal matrix composite includes the step of milling the powder mixture. In an embodiment, the milling of the powder mixture occurs at a speed in a range of about 150 to about 250 rotations per minute (rpm), preferably in a range of about 175 to about 225 rpm. In another embodiment, the milling of the powder mixture occurs at the speed in the range of about 175 to about 225 rpm. In an exemplary embodiment, the milling of the powder mixture occurs at the speed of about 200 rpm. Other ranges are possible.

(63) The method to form the metal matrix composite includes the step of compacting the powder mixture. In an embodiment, the compacting of the powder mixture occurs at a pressure of from 300 to 800 megapascal (MPa). In another embodiment, the compacting of the powder mixture occurs at a pressure of from 400 to 700 MPa. In a more preferred embodiment, the compacting of the powder mixture occurs at a pressure of from 500 to 600 MPa. Other ranges are also possible.

(64) The method to form the metal matrix composite includes the step of sintering the compacted powder mixture. In an embodiment, the sintering of the compacted powder mixture occurs at a temperature of from 300 to 600 degrees Celsius ( C.). In another embodiment, the sintering of the compacted powder mixture occurs at a temperature of from 400 to 500 C. In a more preferred embodiment, the sintering of the compacted powder mixture occurs at a temperature of about 450 C. Other ranges are also possible.

(65) In an embodiment, an MgZr-ES metal matrix composite is disclosed.

(66) In another embodiment, the MgZr-ES metal matrix composite prepared by the method is disclosed.

(67) In one embodiment, the MgZr-ES metal matrix composite has an amount of magnesium from 95 to 97 wt. %, an amount of zirconium from 1 to 2 wt. %, and an amount of ES from 1 to 4 wt. %. In another embodiment, the MgZr-ES metal matrix has an amount of magnesium from 96 to 97 wt. %, an amount of zirconium from 1 to 2 wt. %, and an amount of ES from 2 to 3 wt. %.

(68) In some embodiments, the MgZr-ES metal matrix composite is prepared by the method, wherein the method includes preparing an MgZr-ES powder mixture which comprises the magnesium powder, the zirconium powder and the ES powder using the milling machine, compacting the MgZr-ES powder mixture in the press to form a compacted MgZr-ES powder mixture, and sintering the MgZr-ES compacted powder mixture to form the MgZr-ES composite matrix.

(69) In yet another embodiment, the MgZr-ES metal matrix composite prepared by the method is disclosed, wherein the metal composite matrix has the amount of magnesium from 95 to 97 wt. %, an amount of zirconium from 1 to 2 wt. %, and an amount of ES from 1 to 4 wt. %. In yet another embodiment, the MgZr-ES metal matrix composite prepared by the method, wherein the metal composite matrix has an amount of magnesium from 96 to 97 wt. %, an amount of zirconium from 1 to 2 wt. %, and an amount of ES from 2 to 3 wt. %.

(70) In certain embodiments, Zr and ES are uniformly distributed throughout the MgZr-ES metal matrix composite.

(71) In certain embodiments, the MgZr-ES metal matrix has a densification of from 97 to 99.9% after the sintering of the compacted powder. In some embodiments, the MgZr-ES metal matrix has a densification of from 98 to 99.5% after the sintering of the compacted powder. In some embodiments, the MgZr-ES metal matrix has a densification of from 98.5 to 99.5% after the sintering of the compacted powder.

(72) In certain embodiments, the MgZr-ES metal matrix composite has a first intense peak in a range of 2 value 32 to 36 in the XRD spectrum, and a second intense peak in a range of 2 value 34 to 38 in the XRD spectrum. In some embodiments, the MgZr-ES metal matrix composite has a first intense peak in a range of 2 value 32 to 34 in the XRD spectrum, and a second intense peak in a range of 2 value 36 to 38 in the XRD spectrum. Other ranges are also possible.

(73) In certain embodiments, the MgZr-ES metal matrix composite has a density of from 1.7 g/cm.sup.3 to 1.8 g/cm.sup.3. In some embodiments, the MgZr-ES metal matrix composite has a density of from 1.72 g/cm.sup.3 to 1.78 g/cm.sup.3. In some embodiments, the MgZr-ES metal matrix composite has a density of from 1.74 g/cm.sup.3 to 1.76 g/cm.sup.3. Other ranges are also possible.

(74) In certain embodiments, the MgZr-ES metal matrix composite has a porosity of from 0.5 to 1%, preferably from 0.6 to 0.9%, and more preferably from 0.7 to 0.8%. Other ranges are also possible.

(75) In certain embodiments, the MgZr-ES metal matrix composite has a microhardness of from 40 to 70 HV, further preferably from 45 to 65 HV, more preferably from 50 to 60 HV, and even more preferably from 50 to 55 HV. Other ranges are also possible.

(76) Corrosion performance of the metal matrix composite is conducted in a physiological environment to simulate the performance of the material in biomedical applications. In some embodiments, the MgZr-ES metal matrix composite prepared by the disclosed method has an open circuit voltage (OCP) value of from 1.7 to 1.4 V, preferably from 1.6 to 1.5 V, and more preferably from 1.55 to 1.5 V. In some embodiments, time to achieve a stable OCP value as depicted in FIG. 8 is at least 1 minutes, at least 5 minutes, at least 10 minutes, or at least 15 minutes. In some embodiments, time to achieve a stable OCP value as depicted in FIG. 8 is less than or equal to 20 minutes, less than or equal to 15 minutes, less than or equal to 10 minutes, or less than or equal to 5 minutes. Other ranges are also possible.

(77) Referring to FIG. 9, linear polarization resistance (LPR) curve of the metal matrix composite is illustrated. In some embodiments, the MgZr-ES metal matrix composite has a corrosion potential (E.sub.corr) value of from 1.7 to 1.4 V, preferably from 1.6 to 1.5 V, and more preferably from 1.55 to 1.5 V. In some embodiments, the MgZr-ES metal matrix composite has a current density (I.sub.corr) value of from 1 to 100 microampere per square centimeter (A/cm.sup.2), preferably from 5 to 50 A/cm.sup.2, and more preferably from 10 to 15 A/cm.sup.2. Polarization resistance (Rp), which corresponds to corrosion resistance, is also obtained from the LPR curve as depicted in FIG. 9. In some embodiments, the MgZr-ES metal matrix composite has a Rp value of from 50 to 2000 ohm square centimeter (.Math.cm.sup.2), preferably from 500 to 1700 .Math.cm.sup.2, and more preferably from 1300 to 1500 .Math.cm.sup.2. Other ranges are also possible.

(78) Referring to FIG. 10, potentiodynamic polarization (PDP) curve of the metal matrix composite is illustrated. A positive synergetic effect is observed in the MgZr-ES composite. On one hand, pure Mg shows the most negative E.sub.corr and highest I.sub.corr value as depicted in FIG. 10, indicating that pure Mg has the lowest corrosion-resistant behavior. On the other hand, the MgZr-ES composite exhibits most positive E.sub.corr and lowest I.sub.corr value as depicted in FIG. 10, revealing that the MgZr-ES shows improved corrosion protection performance. The positive synergetic effect of reinforcing the Zr and ES particles into the Mg matrix is further corroborated by comparing the corrosion rate of pure Mg and the MgZr-ES composite using Tafel extrapolation. The estimated corrosion rate for the MgZr-Es is lower than the pure Mg in Hank's medium. In some embodiments, the MgZr-ES metal matrix composite has the E.sub.corr value of from 1.7 to 1.4 V, preferably from 1.6 to 1.5 V, and more preferably from 1.55 to 1.5 V. In some embodiments, the MgZr-ES metal matrix composite has the I.sub.corr value of from 10 to 300 A/cm.sup.2, preferably from 15 to 100 A/cm.sup.2, and more preferably from 20 to 30 A/cm.sup.2. In some embodiments, the MgZr-ES metal matrix composite has a corrosion rate of from 0.5 to 20 millimeter per year (mm/yr), preferably from 1 to 10 mm/yr, and more preferably from 1 to 5 mm/yr. Other ranges are also possible.

(79) Referring to FIG. 12, the bode curve of the metal matrix composite is illustrated. In some embodiments, the MgZr-ES metal matrix composite has a solution resistance (R.sub.s) value of from 80 to 120 .Math.cm.sup.2, preferable from 90 to 110 .Math.cm.sup.2, and more preferably from 95 to 105 .Math.cm.sup.2. In some embodiments, the MgZr-ES metal matrix composite has a charge transfer resistance (R.sub.ct) value of from 100 to 1000 .Math.cm.sup.2, preferable from 300 to 900 .Math.cm.sup.2, and more preferably from 600 to 800 .Math.cm.sup.2. Other ranges are possible.

(80) In an embodiment the composite prepared by the method can be used for biomedical applications including but not limited to bone fixation, orthopedic application such as screws and plates.

EXAMPLES

(81) The following examples describe and demonstrate exemplary embodiments of the method to form metal matrix composite reinforced with eggshell described herein. The examples are provided solely for illustration and are not to be construed as limitations of the present disclosure, as many variations thereof are possible without departing from the spirit and scope of the present disclosure.

Example 1: Preparation of the ES Powder

(82) ES was collected locally and heated for 10 minutes in boiling water, followed by drying at 200 C. for 10 minutes to provide the dried ES. The dried ES was milled in a ball mill under argon atmosphere at 250 rpm using WC vials and WC balls in a planetary Micro Mill PULVERISETTE 7 premium line (FRITSCH, Germany) at ball-to-powder-ratio (BPR) of 10:1 for 20 hours to obtain the ES powder.

Example 2: Preparation of the Metal Matrix Composite and Control Samples

(83) Magnesium powder (99.8 percent purity with an average particle size of 45 m) and Zirconium powder (325 mesh size and 99.8% purity) used for the preparation of the metal matrix composite was supplied by Alfa Aeser.

Example 2a: Preparation of the Mg-2.5ES Composite

(84) Mg-2.5ES (wt. %) powders were blended to provide the blended Mg-2.5ES powder. The blended Mg-2.5ES powder was then loaded into WC vials in a planetary Micro Mill PULVERISETTE 7 premium line (FRITSCH, Germany) and mixed for 2 hours at 200 rpm under an argon atmosphere to provide the Mg-2.5ES powder mixture. The Mg-2.5ES powder mixture was then compacted in a uniaxial press at 550 MPa and held for 5 minutes in tool steel die with a bore diameter of 20 mm to provide the compacted Mg-2.5ES powder mixture. The compacted Mg-2.5ES powder mixture was sintered in a tube furnace (GSL-1700X, MTI) at 450 C. for 2 hours under an argon atmosphere using a heating rate of 10 C./minute to provide the Mg-2.5ES composite.

Example 2b: Preparation of the Mg-1Zr-2.5ES Composite

(85) Mg-1Zr-2.5ES (wt. %) powders were blended to provide the blended Mg-1Zr-2.5ES powder. The blended Mg-1Zr-2.5ES powder was then loaded into WC vials in a planetary Micro Mill PULVERISETTE 7 premium line (FRITSCH, Germany) and mixed for 2 hours at 200 rpm under an argon atmosphere to provide the Mg-1Zr-2.5ES powder mixture. The Mg-1Zr-2.5ES powder mixture was then compacted in a uniaxial press at 550 MPa and held for 5 minutes in tool steel die with a bore diameter of 20 mm to provide the compacted Mg-1Zr-2.5ES powder mixture. The compacted Mg-1Zr-2.5ES powder mixture was sintered in a tube furnace (GSL-1700X, MTI) at 450 C. for 2 hours under an argon atmosphere using a heating rate of 10 C./minute to provide the Mg-1Zr-2.5ES composite.

(86) Control samples of sintered magnesium, zirconium and Mg-1Zr were also prepared for Comparing Properties of the Prepared Metal Matrix Composite.

Example 2c: Preparation of the Sintered Magnesium

(87) Magnesium powder was compacted in a uniaxial press at 550 MPa and held for 5 minutes in tool steel die with a bore diameter of 20 mm to provide compacted magnesium powder. The compacted magnesium powder was sintered in a tube furnace (GSL-1700X, MTI) at 450 C. for 2 hours under an argon atmosphere using a heating rate of 10 C./minute to provide the sintered magnesium.

Example 2d: Preparation of the Sintered Zirconium

(88) Zirconium powder was compacted in a uniaxial press at 550 MPa and held for 5 minutes in tool steel die with a bore diameter of 20 mm to provide compacted zirconium powder. The compacted zirconium powder was sintered in a tube furnace (GSL-1700X, MTI) at 450 C. for 2 hours under an argon atmosphere using a heating rate of 10 C./minute to provide the sintered zirconium.

Example 2e: Preparation of the Sintered Mg-1Zr

(89) Mg-1Zr (wt. %) powders were blended to provide a blended Mg-1Zr powder. The blended Mg-1Zr powder was then loaded into WC vials in a planetary Micro Mill PULVERISETTE 7 premium line (FRITSCH, Germany) and mixed for 2 hours at 200 rpm under an argon atmosphere to provide a Mg-1Zr mixed powder. The Mg-1Zr mixed powder was then compacted in a uniaxial press at 550 MPa and held for 5 minutes in tool steel die with a bore diameter of 20 mm to provide a compacted Mg-1Zr mixed powder. The compacted Mg-1Zr mixed powder was sintered in a tube furnace (GSL-1700X, MTI) at 450 C. for 2 hours under an argon atmosphere using a heating rate of 10 C./minute to provide the sintered Mg-1Zr.

Example 3: Characterization Methods

(90) The prepared materials were characterized in terms of structure, microstructure, densification, and microhardness.

Example 3a: X-Ray Powder Diffraction (XRD) Analysis

(91) The XRD analysis was performed on a Bruker-AXS D8 diffractometer using Cu K (=1.5418 ) radiation. The magnesium powder, zirconium powder, crushed ES, ES powder, sintered magnesium, sintered Mg-1Zr, Mg-2.5ES composite, and Mg-1Zr-2.5ES composite samples were scanned with a 0.02 step size and 2 range of 20 to 90.

(92) Referring now to FIG. 1, all the peaks are clearly shown in XRD pattern of magnesium and zirconium powders. Magnesium powder's XRD pattern reveals presence of (10-10) prism, (0002) basal, and (10-11) pyramidal planes at 2 angles of 32, 34, and 36, respectively [Seetharaman et al., Materials 6, 1940-55, 2013; Jayalakshmi et al., J. Alloys Compd. 565, 56-65, 2013].

(93) Referring now to FIG. 2, the XRD pattern of crushed ES, and ES powder revealed no impurity or extra secondary phases. The full width at half maximum of ES powder was increased after milling, indicating a decrease in the crystallite size and particle size refinement.

(94) Referring now to FIG. 3A-3C, the XRD pattern of Mg-2.5ES composite (FIG. 3B), and Mg-1Zr-2.5ES composite (FIG. 3C) showed no extra peaks, indicating that no additional phases were produced during the sintering process. Magnesium peaks were seen in all samples (i.e. sintered magnesium, sintered Mg-1Zr (FIG. 3A), Mg-2.5ES (FIG. 3B) composite, and Mg-1Zr-2.5E5 composite (FIG. 3C)), however weak ES peaks were observed in Mg-1Zr-2.5ES composite. XRD results also revealed that the texture of the metal matrix composite was altered by presence of zirconium and ES particles. It was reported that reinforcing phases can affect the basal texture of magnesium crystals [Stanford et al., Scr. Mater. 59, 772-5, 2008]. The XRD analysis of magnesium powder (FIG. 1) showed the maximum intensity in the basal plane (0002), indicating a significant basal texture. Additionally, when compared to sintered magnesium powder, it was observed that the peak corresponding to the basal plane (0002) was lowered for Mg-2.5ES composite (FIG. 3B), and Mg-1Zr-2.5ES composite (FIG. 3C), which agrees with a prior finding [Meenashisundaram et al., Mater. Charact. 94, 178-188, 2014].

Example 3b: Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive X-Ray (EDS) Analysis

(95) Microstructural analysis of magnesium powder, zirconium powder, ES powder, and crushed ES was performed on metallographic polished samples under FESEM (FEI Quanta 250 FEG, USA). A distribution of zirconium and ES particles throughout the magnesium matrix in Mg-1Zr-2.5ES powder mixture, Mg-2.5ES powder mixture, Mg-1Zr mixed powder, sintered Mg-1Zr, Mg-1Zr-2.5ES composite, and Mg-2.5ES composite was analyzed by SEM analysis followed by their EDS mapping.

(96) Microstructural examination revealed no indication of micro flaws following compaction and sintering. Additionally, the outer surfaces were smooth and fracture-free circumferentially.

(97) Referring now to FIG. 4A-4D, the SEM micrographs depict morphology of magnesium powder (FIG. 4A), zirconium powder (FIG. 4B), crushed ES (FIG. 4C), and ES powder (FIG. 4D).

(98) Referring now to FIG. 5A-5C, the SEM micrographs and corresponding elemental maps of Mg-2.5ES powder mixture (FIG. 5A), Mg-1Zr mixed powder (FIG. 5B), and Mg-1Zr-2.5ES powder mixture (FIG. 5C) revealed a uniform distribution of zirconium and ES particles throughout the magnesium matrix.

(99) Referring now to FIG. 6A-6D, the SEM micrograph of sintered magnesium (FIG. 6A), Mg-2.5ES composite (FIG. 6B), sintered Mg-1Zr (FIG. 6C), and Mg-1Zr-2.5ES composite (FIG. 6D) revealed a uniform distribution of zirconium and ES particles throughout the magnesium matrix. Magnesium appears to be the gray phase in the SEM micrograph (FIG. 6A), while reinforcement particles appear to be the white phase (FIG. 6B-6D). Additionally, the SEM micrographs revealed no visible porosity in the metal matrix composite.

(100) Referring now to FIGS. 7A & 7B, the SEM micrographs and corresponding elemental maps of Mg-2.5ES composite (FIG. 7A), and Mg-1Zr-2.5ES composite (FIG. 7B) revealed a uniform distribution of zirconium and ES particles throughout the magnesium matrix in the metal matrix composite.

Example 3c: Density Analysis

(101) Archimedes principle was used to determine the density of polished samples by following ASTM B962-17 standards. The sample weight was determined, wherein a density measurement kit integrated within a scale was used to determine the weight of samples taken in air or water [Hussein et al., Mater. Des. 83, 344-351, 2015]. The following equation (1) was used to determine the experimental density of the sample:

(102) $\begin{array}{cc}{}_{\mathrm{ex}}=\left(\frac{A}{A-B}\right)*\left({}_1-{}_a\right)+{}_a& \left(1\right)\end{array}$

(103) Wherein .sub.ex is sample's experimental density, A is weight of the sample measured in air, B is weight of the sample measured in water, .sub.1 is density of water and .sub.a is density of air.

(104) Referring now to Table 1, the experimental density of Mg-1Zr-2.5ES composite was higher than the sintered magnesium. The average relative densities of sintered Mg-1Zr, Mg-2.5ES composite, and Mg-1Zr-2.5ES composite were determined to be 99.65%, 98.9%, and 99.2%, respectively. The results indicated that a near-dense material was manufactured utilizing the processing conditions of the invention. However, the observed porosity of 1.1% in the Mg-2.5ES composite could be a result of ES particles agglomerating in the magnesium matrix. The reduced porosity (i.e. 0.8%) of the Mg-1Zr-2.5ES composite may be a result of the improved interfacial bonding between the ES and the magnesium matrix, which is useful in suppressing grain development during the sintering. The metal matrix composite showed density close to cancellous bone and cortical bone.

(105) TABLE-US-00001 TABLE 1 Density and porosity of the analyzed materials. Theoretical Experimental density density Porosity Material (g/cm.sup.3) (g/cm.sup.3) (%) Sintered magnesium 1.738 1.738 0.0 Mg-1Zr 1.75 1.74 0.343 Mg-2.5ES 1.751 1.73 1.1 Mg-1Zr-2.5ES 1.764 1.75 0.80 Cortical bone 1.8-2.0* Cancellous bone 1.0-1.4* *Bommala et al., J. Magnes. Alloy. 7, 72-79, 2019

Example 3d: Microhardness Analysis

(106) Microhardness was determined using HV test (ASTM E384-08) by employing a 50-gf load and a dwell length of 15 seconds. Each sample was tested at least eight times in a straight line and an average value was calculated.

(107) Referring now to Table 2, the microhardness value of sintered magnesium, sintered Mg-1Zr, Mg-2.5ES composite, and Mg-1Zr-2.5ES composite is shown in Table 2. An increase in the microhardness value of Mg-2.5ES composite (+3%), and Mg-1Zr-2.5ES composite (+6.4%) was observed when compared to sintered magnesium.

(108) TABLE-US-00002 TABLE 2 Microhardness value of the analyzed materials. Microhardness Material (HV) Sintered magnesium 49.72 Mg-1Zr 56.59 (+13.8%) Mg-2.5ES 51.28 (+3%) Mg-1Zr-2.5ES 52.89 (+6.4%)

Example 3e: In-Vitro Corrosion Analysis in a Physiological Medium

(109) The bio-corrosion performance of the metal matrix composite was assessed by analyzing their in-vitro corrosion properties. Corrosion-resistant behavior in the physiological medium was evaluated using an electrochemical station, Gamry Potentiostat instrument through the three-electrode cell setup in which the metal matrix composite behave as a working electrode, whereas graphite rod and saturated calomel electrode used as counter and reference electrodes, respectively. Hank's solution was prepared using the previous report [Qiu et al., Mater. Sci. Eng. C 36, 65-76, 2014] and the exposed area was about 1.76 cm.sup.2. Before all the electrochemical testing, open circuit potential (OCP) was monitored for about 30 minutes to attain a steady-state of the investigated system. Linear polarization resistance (LPR) measurements were achieved by selecting a potential of 25 mV with a scan rate of 0.1967 mV/s. Electrochemical impedance spectroscopy (EIS) was performed by selecting a frequency region of 1 kHz to 1 mHz using 10 mV perturbation signal. Potentiodynamic polarization (PDP) measurements were carried out by applying a potential of 0.250 mV vs OCP with a scan rate of 1 mV/s. All the test results were analyzed using an inbuilt software, Echem analysis, and the obtained results were replicated to ensure the reproducibility of the data.

(110) Referring now to FIG. 8, the OCP values with a function of the immersion period were monitored as it provides a preliminary information on the corrosion-resistant and the obtained curves are presented in FIG. 8. The period required to achieve a stable OCP value is varied from 1 minute to 10 minutes. Sintered magnesium acquired more time to reach a steady-state OCP than sintered Mg-1Zr, Mg-2.5ES composite, and Mg-1Zr-2.5ES composite. In particular, Mg-1Zr-2.5ES composite engaged minimum time to attain a steady-state with a lesser degree of fluctuations. Furthermore, a noble corrosion potential of 1.5126 V was detected for Mg-1Zr-2.5ES composite as compared with sintered magnesium. The obvious shift of OCP was identified in the case of Mg-1Zr-2.5ES composite, primarily indicating enhanced corrosion-resistance obtained by addition of zirconium and ES particles.

(111) Referring now to FIG. 9, which illustrate LPR curves of sintered magnesium, sintered Mg-1Zr, Mg-2.5ES composite, and Mg-1Zr-2.5ES composite in Hank's medium.

(112) Referring now to Table 3, the estimated parameters such as corrosion current density (i.sub.corr), corrosion potential (E.sub.corr), and polarization resistance (R.sub.p) of sintered magnesium, sintered Mg-1Zr, Mg-2.5ES composite, and Mg-1Zr-2.5ES composite are given in Table 3. Mg-1Zr-2.5ES composite showed a positive shift in E.sub.corr value when compared with sintered magnesium, which reveals the improved electrochemical stability in Hank's medium. Further, i.sub.corr value of sintered magnesium was found to be about 80.5190 A cm.sup.2, whereas this value was pointedly reduced to 12.3401 A cm.sup.2 for Mg-1Zr-2.5ES composite, revealing the reduction in the corrosion rate. In addition, the R.sub.p value of Mg-1Zr-2.5ES composite was found to be higher than the sintered magnesium, which further validated the improvement in the corrosion-resistant behavior.

(113) TABLE-US-00003 TABLE 3 Electrochemical parameters from LPR curve. E.sub.corr I.sub.corr .sub.a .sub.b R.sub.p Substrate (mV) (A cm.sup.2) (mV/dec) (mV/dec) ( cm.sup.2) Sintered 1.6352 80.5190 89 57 187.35 magnesium Mg-1Zr 1.5665 43.8972 64 73 430.91 Mg-2.5ES 1.5989 51.8245 82 93 365.21 Mg-1Zr-2.5ES 1.554 12.3401 74 88 1413.05

(114) Referring now to FIG. 10, which illustrate the representative PDP curves of sintered magnesium, sintered Mg-1Zr, Mg-2.5ES composite, and Mg-1Zr-2.5ES composite in Hank's medium.

(115) Referring now to Table 4, the estimated values from the Tafel extrapolation analysis of the PDP curves are summarized. It is well known that the magnesium exhibits an electrochemical activity without showing passivation behavior [Cao et al., Corros. Sci. 111, 835-845, 2016]. The most negative E.sub.corr and highest i.sub.corr value was shown by sintered magnesium, revealing its lowest corrosion-resistant behavior. Whereas Mg-1Zr-2.5ES composite exhibited most positive E.sub.corr value of 1.5021 V and lowest i.sub.corr values of 23.1293 A cm.sup.2, validating the improvement of in-vitro corrosion protection performance. It's also obvious from Table 4 that the estimated corrosion rate for the metal matrix composite is lower than the sintered magnesium, further corroborating the positive synergetic effect of the zirconium and ES particles in the magnesium matrix in enhancing the anti-corrosion behavior in Hank's medium.

(116) TABLE-US-00004 TABLE 4 Electrochemical parameters from Tafel plot analysis. E.sub.corr I.sub.corr .sub.a .sub.b Corrosion Rate Substrate (mV) (A cm.sup.2) (mV/dec) (mV/dec) (mm/year) Sintered magnesium 1.5984 264.9602 79 94 12.1031 Mg-1Zr 1.5417 67.2034 73 86 3.0326 Mg-2.5ES 1.5893 84.3321 65 93 3.8103 Mg-1Zr-2.5ES 1.5021 23.1293 78 81 1.0450

(117) Referring now to FIG. 11, Nyquist curves exhibited one distorted capacitive arc at high and intermediate frequency regions followed by an inductive loop at the low-frequency region. The capacitive arc at high-frequency regions is attributed to the electrochemical double layer and charge transfer response, while the inductive loop at low frequencies is ascribed to the attached magnesium intermediates including Mg.sup.+ and Mg(OH).sup.+ ions on substrate's surface [Jayaraj et al., Corros. Sci. 113, 104-115, 2016].

(118) Referring now to FIG. 12, impedance of the magnesium was found to be about 300 cm.sup.2, whereas the impedance of the Mg-1Zr-2.5ES composite was about 700 cm.sup.2 in the same frequencies. A high value of the impedance modulus in the low frequencies is a general indicator of its better performance, and considering the impedance values from the FIG. 12, the protective performance offered by these materials can be ranked as sintered magnesium <Mg-2.5ES <Mg-1Zr <Mg 1-Zr-2.5ES.

(119) To analyze the obtained EIS curves further, an equivalent circuit fitting procedure was executed by selecting the appropriate EIS model and the estimated parameters are shown in Table 5.

(120) Referring now to Table 5, comparing the obtained R.sub.ct values as shown in Table 5, it's clear that Mg-1Zr-2.5ES composite displayed the highest R.sub.ct values, validating its enhanced corrosion-resistant performance in Hank's medium. Further, CPE.sub.dl value of Mg-1Zr-2.5ES composite was found to be one order magnitude lower than sintered magnesium, verifying that infusion of violent components from electrolyte towards the magnesium surface proscribed by the enhanced barrier performance due to the zirconium and ES particles in the magnesium matrix.

(121) TABLE-US-00005 TABLE 5 EIS parameters from the equivalent circuit fitting procedure. R.sub.s R.sub.ct CPE.sub.dl Substrate ( cm.sup.2) ( cm.sup.2) (.sup.1 cm.sup.2s.sup.n) n.sub.dl Sintered magnesium 98.4326 302.4194 112.9836 0.96 Mg-1Zr 101.7658 556.4390 50.4398 0.97 Mg-2.5ES 104.2954 328.4309 73.2905 0.96 Mg-1Zr-2.5ES 101.3496 701.2945 32.6839 0.97

(122) Obviously, numerous modifications and variations of the present disclosure are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.