LEAD-FREE PIEZOELECTRIC CERAMIC SENSOR MATERIAL AND A PREPARATION METHOD THEREOF

Abstract

A lead-free piezoelectric ceramic sensor material and a preparation method thereof, and relates to the technical field of piezoelectric ceramic processing. The main raw materials of the lead-free piezoelectric ceramic sensor material disclosed in the present disclosure are a barium carbonate, a calcium carbonate, a zirconia, a titanium dioxide, a strontium carbonate, an oxidation bait, a bismuth oxide, a composite binder and a dispersant agent. The preparation method is prepared through the steps of preparing ingredients, ball milling, granulating and tableting, debinding, and sintering, and the lead-free piezoelectric ceramic sensor material can be made into a lead-free piezoelectric sensor through applying an electrode and electrode polarizing. The present disclosure has an excellent compactness and a good chemical stability. And the piezoelectric sensor made of the lead-free piezoelectric ceramic sensor material has a high sensitivity, a strong working stability, an excellent piezoelectric and has a high Curie temperature.

Claims

1. A lead-free piezoelectric ceramic sensor material, wherein: in terms of a mass percentage, the lead-free piezoelectric ceramic sensor material is composed of following main raw materials: barium carbonate 32.8-35.3%, calcium carbonate 34.4-38.7%, zirconia 8.5-10.3%, titanium dioxide 8.6-11.0%, strontium carbonate 3.8-5.2%, oxidation bait 2.4-3.7% and bismuth oxide 1.5-4.2%; the lead-free piezoelectric ceramic sensor material includes lithium oxide, yttrium oxide, composite binder and dispersant agent.

2. The lead-free piezoelectric ceramic sensor material according to claim 1, wherein: a mass of the lithium oxide is 0.21-0.35% of a total amount of a main raw material, and the mass of the yttrium oxide is 0.18-0.29% of the total amount of the main raw material, the mass of the composite binder is 3.5-4.5% of the total amount of the main raw material and the mass of the dispersant agent is 0.3-0.6% of the total amount of the main raw material.

3. The lead-free piezoelectric ceramic sensor material according to claim 2, wherein: the composite binder is prepared by reacting polyvinyl alcohol with polysiloxane compound under an action of triethanolamine; the polysiloxane compound is a waterborne film-forming protective agent R-23 produced by a Jining Huakai Resin Co., Ltd., and a mass ratio of the polyvinyl alcohol and the polysiloxane compound is 1:(0.5-0.8).

4. The lead-free piezoelectric ceramic sensor material according to claim 3, wherein: a preparation method of the composite binder, comprising: adding 2 times a mass of the triethanolamine into the polyvinyl alcohol under a room temperature, adding organosiloxane compound, and then stirring a mixture of the polyvinyl alcohol, the triethanolamine and the organosiloxane compound under a constant temperature of 60° C. for 1.5 hours, filtering, washing with deionized water, and drying to obtain a required composite binder.

5. The lead-free piezoelectric ceramic sensor material according to claim 2, wherein: the dispersant agent is one or more of sodium citrate, sodium silicate, sodium hexametaphosphate or sodium tripolyphosphate.

6. A preparation method of the lead-free piezoelectric ceramic sensor material according to claim 1, comprising the following steps: (1) preparing ingredients: according to the mass percentage, weighing and taking a required mass of the barium carbonate, the calcium carbonate, the zirconia, the titanium dioxide, the strontium carbonate, the oxidation bait and the bismuth oxide, mixing uniformly to prepare a mixed raw material; (2) ball milling: adding the mixed raw material into a high-energy ball mill, then adding ⅓ of a required mass of the dispersant agent, starting a wet ball milling, and a mass ratio of the mixed raw material and the deionized water is 1:1, a ball milling rate is 320-380 r/min, preforming a ball milling for 4-5 h; then continuing to adding the lithium oxide, the yttrium oxide and a remaining ⅔ mass dispersant agent into the high-energy ball mill, starting a secondary ball milling and the ball milling rate is 320-380 r/min, and preforming the ball milling for 10 h; (3) granulating and tableting: suction filtering a slurry after ball milling, and then processing the slurry after ball milling into a 400 mesh granular ceramic powder through a centrifugal spray dryer; uniformly mixing the 400 mesh granular ceramic powder with absolute ethyl alcohol in a mass ratio of 1:0.3, adding the composite binder, and after mixing uniformly, heating up to 70° C., stirring for 1 h, and then granulating; and placing pellets in a stainless steel mold and pressing the pellets into a green body with a required thickness under a pressure of 12-18 MPa; (4) debinding: putting the green body in a heating furnace, heating up to 200-250° C., performing a heat preservation for 60 minutes; and then heating up to 500-600° C. at a rate of 3-5° C./min and performing the heat preservation for 2 h; then heating up to 720-780° C. and performing the heat preservation for 3 h; (5) sintering: putting a debinding green body in a clamp pot, covering tightly, and sintering at 1050-1180° C., a heat preservation time is 3-4 h; and then naturally cooling the debinding green body to the room temperature, finishing a preparation of the lead-free piezoelectric ceramic sensor material.

7. The preparation method of the lead-free piezoelectric ceramic sensor material according to claim 6, in the S2, in a process of the wet ball milling, a ball milling medium is a steel ball, and a mass ratio of the steel ball to the mixed raw material is 5:1.

8. The preparation method of the lead-free piezoelectric ceramic sensor material according to claim 6, in the S2, in a process of the secondary ball milling, adding the deionized water into the high-energy ball mill, the mass of the deionized water is a half of the mass of the mixed raw material.

9. A preparation method for preparing the lead-free piezoelectric ceramic sensor with the lead-free piezoelectric ceramic sensor material according to claim 6, comprising the following steps: (6) applying an electrode: cleaning the lead-free piezoelectric ceramic sensor material, and then using a screen printing technology to print a silver paste on an upper surface and a lower surface of the lead-free piezoelectric ceramic sensor material, and putting a printed silver product in the heating furnace, heating up to 800° C., performing the heat preservation for 50-60 minutes, waiting the printed silver product cooling to the room temperature, and finishing a piezoelectric ceramic silver sheet; (7) polarizing: polarizing the piezoelectric ceramic silver sheet by a direct current electric field, a polarization temperature is from 110 to 130° C., a polarization time is 30 min, and a polarization field strength is 3-6 kV/mm, and preparing the lead-free piezoelectric ceramic sensor.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The following describes the technical solutions in the embodiments of the present disclosure clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present disclosure.

[0028] The lead-free piezoelectric ceramic sensor material and the lead-free piezoelectric ceramic sensor of the present disclosure and the preparation method thereof will be described below with reference to specific embodiments.

Embodiment 1

[0029] the preparation method of the lead-free piezoelectric ceramic sensor material, comprising the following steps:

[0030] (1) preparing ingredients: weighing and taking 328 g BaCO.sub.3, 387 g CaCO.sub.3, 85 g ZrO.sub.2, 110 g TiO.sub.2, 38 g SrCO.sub.3, 37 g Er.sub.2O.sub.3 and 15 g Bi.sub.2O.sub.3 and mixing them uniformly to prepare the mixed raw material.

[0031] (2) Ball milling: adding the mixed raw material into a high-energy ball mill, and then adding 2 g sodium hexametaphosphate, starting a wet ball milling and the ball milling medium is steel ball, and adding 5 kg steel balls and 1 kg deionized water, a ball milling rate is 320-380 r/min, preforming the ball milling for 4-5 h. Continuing to adding 3.5 g Li.sub.2O, 2.9 g Y.sub.2O.sub.3 and 4 g sodium hexametaphosphate into the high-energy ball mill, starting a secondary ball milling and during the second ball milling process, 0.5 kg of deionized water needs adding into the high-energy ball mill, and the ball milling rate is 320-380 r/min, and preforming the ball milling for 10 h.

[0032] (3) Granulating and tableting: suction filtering a slurry after ball milling, and then processing the slurry after ball milling into a 400 mesh granular ceramic powder through a centrifugal spray dryer, uniformly mixing the 400 mesh granular ceramic powder with an absolute ethyl alcohol in a mass ratio of 1:0.3, adding 35 g composite binder, and after mixing uniformly, heating up to 70° C., stirring for 1 h, and then granulating; and placing pellets in a stainless steel mold and pressing the pellets into a green body with a required thickness under a pressure of 12-18 MPa.

[0033] The composite binder is prepared by reacting a polyvinyl alcohol with a polysiloxane compound under an action of a triethanolamine; the polysiloxane compound is a waterborne film-forming protective agent R-23 produced by a Dining Huakai Resin Co., Ltd. The preparation method of the composite binder, comprising: adding 200 g triethanolamine into 100 g polyvinyl alcohol under a room temperature, and then adding 50 g organosiloxane compound, and then stirring a mixture of the polyvinyl alcohol, the triethanolamine and an organosiloxane compound under a constant temperature of 60° C. for 1.5 hours, filtering, washing with a deionized water, and drying to obtain a required composite binder.

[0034] (4) Debinding: putting the green body in a heating furnace, heating up to 200-250° C., performing a heat preservation for 60 minutes; and then heating up to 500-600° C. at a rate of 5° C./min and performing the heat preservation for 2 h; then heating up to 720-780° C. and performing the heat preservation for 3 h.

[0035] (5) Sintering: putting a debinding green body in a clamp pot, covering tightly, and sintering at 1180° C., a heat preservation time is 3-4 h; and then naturally cooling the debinding green body to the room temperature, and finishing a preparation of the lead-free piezoelectric ceramic sensor material A1.

Embodiment 2

[0036] the preparation method of the lead-free piezoelectric ceramic sensor material, comprising the following steps:

[0037] (1) preparing ingredients: weighing and taking 353 g BaCO.sub.3, 344 g CaCO.sub.3, 103 g ZrO.sub.2, 86 g TiO.sub.2, 52 g SrCO.sub.3, 24 g Er.sub.2O.sub.3 and 38 g Bi.sub.2O.sub.3, and mixing them uniformly to prepare the mixed raw material.

[0038] (2) Ball milling: adding the mixed raw material into a high-energy ball mill, and then adding 1 g sodium silicate, starting a wet ball milling and the ball milling medium is steel ball, and adding 5 kg steel balls and 1 kg deionized water, a ball milling rate is 320-380 r/min, preforming the ball milling for 4-5 h. Continuing to adding 2.1 g Li.sub.2O, 1.8 g Y.sub.2O.sub.3 and 2 g sodium silicate into the high-energy ball mill, starting a secondary ball milling and during the second ball milling process, 0.5 kg of deionized water needs adding into the high-energy ball mill, and the ball milling rate is 320-380 r/min, and preforming the ball milling for 10 h.

[0039] (3) Granulating and tableting: suction filtering a slurry after ball milling, and then processing the slurry after ball milling into a 400 mesh granular ceramic powder through a centrifugal spray dryer, uniformly mixing the 400 mesh granular ceramic powder with an absolute ethyl alcohol in a mass ratio of 1:0.3, adding 45 g composite binder, and after mixing uniformly, heating up to 70° C., stirring for 1 h, and then granulating; and placing pellets in a stainless steel mold and pressing the pellets into a green body with a required thickness under a pressure of 12-18 MPa.

[0040] The composite binder is prepared by reacting a polyvinyl alcohol with a polysiloxane compound under an action of a triethanolamine. The mass ratio of the polyvinyl alcohol and the polysiloxane compound is 1:0.8.

[0041] (4) Debinding: putting the green body in a heating furnace, heating up to 200-250° C., performing a heat preservation for 60 minutes; and then heating up to 500-600° C. at a rate of 4° C./min and performing the heat preservation for 2 h; then heating up to 720-780° C. and performing the heat preservation for 3 h.

[0042] (5) Sintering: putting a debinding green body in a clamp pot, covering tightly, and sintering at 1150° C., a heat preservation time is 3-4 h; and then naturally cooling the debinding green body to the room temperature, and finishing a preparation of the lead-free piezoelectric ceramic sensor material A2.

Embodiment 3

[0043] the preparation method of the lead-free piezoelectric ceramic sensor material, comprising the following steps:

[0044] (1) preparing ingredients: weighing and taking 336 g BaCO.sub.3, 364 g CaCO.sub.3, 92 g ZrO.sub.2, 92 g TiO.sub.2, 48 g SrCO.sub.3, 26 g Er.sub.2O.sub.3 and 42 g Bi.sub.2O.sub.3 and mixing them uniformly to prepare the mixed raw material.

[0045] (2) Ball milling: adding the mixed raw material into a high-energy ball mill, and then adding 1.5 g sodium tripolyphosphate, starting a wet ball milling and the ball milling medium is steel ball, and adding 5 kg steel balls and 1 kg deionized water, a ball milling rate is 320-380 r/min, preforming the ball milling for 4-5 h. Continuing to adding 3 g Li.sub.2O, 2.5 g Y.sub.2O.sub.3 and 3 g sodium tripolyphosphate into the high-energy ball mill, starting a secondary ball milling and during the second ball milling process, 0.5 kg of deionized water needs adding into the high-energy ball mill, and the ball milling rate is 320-380 r/min, and preforming the ball milling for 10 h.

[0046] (3) Granulating and tableting: suction filtering a slurry after ball milling, and then processing the slurry after ball milling into a 400 mesh granular ceramic powder through a centrifugal spray dryer, uniformly mixing the 400 mesh granular ceramic powder with an absolute ethyl alcohol in a mass ratio of 1:0.3, adding 38 g composite binder, and after mixing uniformly, heating up to 70° C., stirring for 1 h, and then granulating; and placing pellets in a stainless steel mold and pressing the pellets into a green body with a required thickness under a pressure of 12-18 MPa.

[0047] The composite binder is prepared by reacting a polyvinyl alcohol with a polysiloxane compound under an action of a triethanolamine. The mass ratio of the polyvinyl alcohol and the polysiloxane compound is 1:0.6.

[0048] (4) Debinding: putting the green body in a heating furnace, heating up to 200-250° C., performing a heat preservation for 60 minutes; and then heating up to 500-600° C. at a rate of 3° C./min and performing the heat preservation for 2 h; then heating up to 720-780° C. and performing the heat preservation for 3 h.

[0049] (5) Sintering: putting a debinding green body in a clamp pot, covering tightly, and sintering at 1050° C., a heat preservation time is 3-4 h; and then naturally cooling the debinding green body to the room temperature, finishing a preparation of the lead-free piezoelectric ceramic sensor material A3.

Embodiment 4

[0050] the preparation method of the lead-free piezoelectric ceramic sensor material, comprising the following steps:

[0051] (1) preparing ingredients: weighing and taking 349 g BaCO.sub.3, 356 g CaCO.sub.3, 87 g ZrO.sub.2, 108 g TiO.sub.2, 41 g SrCO.sub.3, 36 g Er.sub.2O.sub.3 and 23 g Bi.sub.2O.sub.3, and mixing them uniformly to prepare the mixed raw material.

[0052] (2) Ball milling: adding the mixed raw material into a high-energy ball mill, and then adding 2 g sodium citrate, starting a wet ball milling and the ball milling medium is steel ball, and adding 5 kg steel balls and 1 kg deionized water, a ball milling rate is 320-380 r/min, preforming the ball milling for 4-5 h. Continuing to adding 2.6 g Li.sub.2O, 2.8 g Y.sub.2O.sub.3 and 4 g sodium citrate into the high-energy ball mill, starting a secondary ball milling and during the second ball milling process, 0.5 kg of deionized water needs adding into the high-energy ball mill, and the ball milling rate is 320-380 r/min, and preforming the ball milling for 10 h.

[0053] (3) Granulating and tableting: suction filtering a slurry after ball milling, and then processing the slurry after ball milling into a 400 mesh granular ceramic powder through a centrifugal spray dryer, uniformly mixing the 400 mesh granular ceramic powder with an absolute ethyl alcohol in a mass ratio of 1:0.3, adding 42 g composite binder, and after mixing uniformly, heating up to 70° C., stirring for 1 h, and then granulating; and placing pellets in a stainless steel mold and pressing the pellets into a green body with a required thickness under a pressure of 12-18 MPa.

[0054] The composite binder is prepared by reacting a polyvinyl alcohol with a polysiloxane compound under an action of a triethanolamine. The mass ratio of the polyvinyl alcohol and the polysiloxane compound is 1:0.5.

[0055] (4) Debinding: putting the green body in a heating furnace, heating up to 200-250° C., performing a heat preservation for 60 minutes; and then heating up to 500-600° C. at a rate of 4° C./min and performing the heat preservation for 2 h; then heating up to 720-780° C. and performing the heat preservation for 3 h.

[0056] (5) Sintering: putting a debinding green body in a clamp pot, covering tightly, and sintering at 1100° C., a heat preservation time is 3-4 h; and then naturally cooling the debinding green body to the room temperature, finishing a preparation of the lead-free piezoelectric ceramic sensor material A4.

[0057] Comparative example 1: a piezoelectric ceramic sensor material a1, whose preparation method is the same as that in the embodiment 3, while, the difference is that in the comparative example 1, the composition of the mixed raw materials is 349 g BaCO.sub.3, 356 g CaCO.sub.3, 87 g ZrO.sub.2 and 108 g TiO.sub.2.

[0058] Comparative example 2: a piezoelectric ceramic sensor material a2, whose material and preparation method are the same as that in the embodiment 3, while, the difference is that SrCO.sub.3 is not added into the comparative example 2.

[0059] Comparative example 3: a piezoelectric ceramic sensor material a3, whose material and preparation method are the same as that in the embodiment 3, while the difference is that Er.sub.2O.sub.3 and Bi.sub.2O.sub.3 are not added into the comparative example 3.

[0060] Comparative example 4: a piezoelectric ceramic sensor material a4, whose material and preparation method are the same as that in the embodiment 3, except that the composite binder in the comparative example 4 is polyvinyl alcohol.

[0061] Testing the performance of the piezoelectric ceramic sensor materials prepared in the foregoing embodiments 1-4 and comparative examples 1-4, and the test results are shown in Table 1 below:

TABLE-US-00001 fracture toughness value bending strength (25° C., KIC/MPa .Math. m.sup.1/2) σ/MPa parallel perpendicular parallel perpendicular A1 1.38 0.77 45.16 42.57 A2 1.46 0.86 49.25 45.17 A3 1.65 0.97 52.38 47.62 A4 1.57 0.93 50.78 46.94 a1 1.13 0.66 41.56 38.22 a2 1.24 0.70 42.97 40.12 a3 1.39 0.81 46.51 42.84 a4 0.95 0.52 39.69 36.47

[0062] It can be seen from the test results in Table 1 that the piezoelectric ceramic sensor material prepared by the present disclosure has excellent mechanical strength and toughness. The composite binder has greatly improved strength and toughness of the present disclosure, and the addition of the strontium carbonate also improve the mechanical strength and fracture toughness of the present disclosure.

[0063] Cleaning the lead-free piezoelectric ceramic sensor material made in the embodiments 1-4 and comparative examples 1-4, and then using a screen printing technology to print a silver paste on an upper surface and a lower surface of the lead-free piezoelectric ceramic sensor material, and putting a printed silver product in the heating furnace, heating up to 800° C., performing the heat preservation for 50-60 minutes, waiting the printed silver product cooling to the room temperature, and finishing a piezoelectric ceramic silver sheet. Polarizing the piezoelectric ceramic silver sheet by a direct current electric field, a polarization temperature is from 110 to 130° C., a polarization time is 30 min, and a polarization field strength is 3-6 kV/mm, and finally the lead-free piezoelectric ceramic sensor is prepared. Wherein, the lead-free piezoelectric ceramic sensors prepared by the above-mentioned electrode application and polarization methods in the embodiments 1-4 are B1, B2, B3, and B4 respectively. And the lead-free piezoelectric ceramic sensors prepared by the above-mentioned electrode application and polarization methods in the comparative examples 1-4 are b1, b2, b3 and b4 respectively.

[0064] Testing the performance of the piezoelectric ceramic sensors prepared in the foregoing embodiments 1-4 and comparative examples 1-4, and the test results are shown in Table 2 below:

TABLE-US-00002 electro- mechanical piezoelectric dielectric dielectric coupling Curie coefficient constant loss coefficient tempertature d33/pC/N ε33T/ε0 tgδ Kp Tc/° C. B1 552 3764 0.25 0.65 242 B2 564 3859 0.23 0.72 249 B3 586 4122 0.15 0.79 252 B4 570 4035 0.18 0.78 245 b1 432 2560 0.62 0.51 192 b2 526 3420 0.38 0.62 240 b3 482 3080 0.42 0.58 203 b4 530 3525 0.28 0.64 231

[0065] It can be seen from the test results in Table 2 that the piezoelectric ceramic sensor has a higher piezoelectric coefficient, that is, higher sensitivity and lower dielectric loss, which can ensure that the piezoelectric ceramic sensor loses less internal energy during long-term operation. Further, the piezoelectric ceramic sensor will not be broken due to its heating, and has a higher Curie temperature, which can still have better piezoelectric performance at higher temperatures. The present disclosure improves the piezoelectric performance of the piezoelectric sensor and reduces the dielectric loss by adding strontium carbonate. And by adding and synergizing Er.sub.2O.sub.3 and Bi.sub.2O.sub.3, the present disclosure significantly increases the piezoelectric coefficient and Curie temperature of the piezoelectric sensor and reduces the dielectric loss, and further, the present disclosure can enjoy a higher sensitivity.

[0066] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope of the specification.

[0067] The above-mentioned examples only express several embodiments of the present disclosure, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the present disclosure. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present disclosure, several modifications and improvements can be made, and these all fall within the protection scope of the present disclosure.