Raw material for metal porous body and metal porous body

Abstract

A material for porous metal body having a coil shape of a wire material wound in a helical shape, made of metal which having good thermal conductivity and can join by sintering; an average wire diameter Dw of the wire material is 0.05 mm to 2.00 mm inclusive, an average coil outer diameter Dc is 0.5 mm to 10.0 mm inclusive, a coil length L of 1 mm to 20 mm inclusive, and a winding number N is 1 to 10; and the plurality of materials for porous metal body are combined and sintered to form a metal porous body having a plurality of pores so that a pore ratio of the metal porous body is facilitated to be controlled.

Claims

1. A material for metal porous body for composing a metal porous body having a plurality of pores, which is a wire material having a coil shape wound in a helical shape, wherein the wire material has an average wire diameter Dw of not less than 0.05 mm and not more than 2.00 mm; the coil shape has an average coil outer diameter Dc of not less than 0.5 mm and not more than 10.0 mm, a coil length L of not less than 1 mm and not more than 20 mm, and a coil winding number N of not less than 1 and not more than 10; wherein the material for metal porous body in a state in which one end thereof along a direction following the coil length L is supported in a cantilever manner and the other end is deflected with a deflection amount δ by its own weight, a deflection ratio (δ/L) of the coil length L and the deflection amount δ is not more than 0.20.

2. The material for metal porous body according to claim 1, wherein an aspect ratio (L/Dc) of the average coil outer diameter Dc and the coil length L be not less than 0.1 and not more than 10.0.

3. The material for metal porous body according to claim 1, wherein a porosity of the material for metal porous body Q (%) is not less than 30.0% and not more than 99.9%, where an occupied volume Vc (mm.sup.3) is [L×π×(Dc/2).sup.2]; a material volume Vw (mm.sup.3) is {[π×(Dw/2).sup.2]×(Dc−Dw)×π×N}; and the porosity Q (%) is [1−(Vw/Vc)]×100.

4. The material for metal porous body according to claim 1, wherein a pitch ratio (P/Dw) of a pitch P and the average wire diameter Dw is not less than 1 and not more than 50, where the pitch P is an interval between turns in a direction of the coil length L.

5. The material for metal porous body according to claim 1, wherein a cross sectional shape of the wire material is a polygon having six or less corner parts and a curvature radius of each of the corner parts is not more than 0.1 mm.

6. The metal porous body formed by combining and sintering the material for metal porous body according to claim 1.

7. The material for metal porous body according to claim 2, wherein a porosity of the material for metal porous body Q (%) is not less than 30.0% and not more than 99.9%, where an occupied volume Vc (mm.sup.3) is [L×π×(Dc/2).sup.2]; a material volume Vw (mm.sup.3) is {[π×(Dw/2).sup.2]×(Dc−Dw)×π×N}; and the porosity Q (%) is [1−(Vw/Vc)]×100.

8. The material for metal porous body according to claim 2, wherein a pitch ratio (P/Dw) of a pitch P and the average wire diameter Dw is not less than 1 and not more than 50, where the pitch P is an interval between turns in a direction of the coil length L.

9. The material for metal porous body according to claim 3, wherein a pitch ratio (P/Dw) of a pitch P and the average wire diameter Dw is not less than 1 and not more than 50, where the pitch P is an interval between turns in a direction of the coil length L.

10. The material for metal porous body according to claim 2, wherein a cross sectional shape of the wire material is a polygon having six or less corner parts and a curvature radius of each of the corner parts is not more than 0.1 mm.

11. The metal porous body formed by combining and sintering the material for metal porous body according to claim 2.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 It is a schematic view of a material for metal porous body of the present invention.

(2) FIG. 2 It is a side view of the material for metal porous body shown in FIG. 1 in an axial direction.

(3) FIG. 3 It is an end view taken along the line A-A of the material for metal porous body shown in FIG. 2.

(4) FIG. 4 It is a lateral cross sectional view of a wire material shown in FIG. 1.

(5) FIG. 5 It is a schematic view explaining a space formed by stacking the plurality of materials for metal porous body.

(6) FIG. 6 It is a schematic view explaining a deflection amount of the material for metal porous body.

(7) FIG. 7 It is a photograph of the material for metal porous body.

(8) FIG. 8 It is a photograph in a lateral cross section of the material for metal porous body.

(9) FIG. 9 It is a schematic view explaining a metal porous body formed by combining a plurality of the materials for metal porous body shown in FIG. 1.

(10) FIG. 10 It is a schematic view explaining a metal porous body in another embodiment.

(11) FIG. 11 It is a schematic view explaining a metal porous body in another embodiment.

DESCRIPTION OF EMBODIMENTS

(12) Below, embodiments of the present invention will be explained. FIG. 1 shows a material for metal porous body 10 of an embodiment of the present invention. FIG. 9 shows a metal porous body 101 manufactured by using the materials for metal porous body 10. As shown in the schematic view in FIG. 9, the plurality of materials for metal porous body 10 are used by being combined for manufacturing the metal porous body 101 having a plurality of pores.

(13) —Structure of Material for Metal Porous Body—

(14) As shown in the schematic view in FIG. 1 and FIG. 2, the material for metal porous body 10 is a small piece having a coil shape in which a wire-shaped wire material 11 made of metal material is wound in a helical shape. The wire material 11 is made of metal material having high thermal conductivity and bondable by sintering: for example, aluminum and aluminum alloy can be suitably used.

(15) A cross sectional shape (a lateral cross section) of the wire material 11 forming the material for metal porous body 10 is not limited to a perfect circle; it may be a triangle shape as shown in FIG. 3 and FIG. 4, for example. The cross sectional shape of the wire material 11 is a polygon with six or less corner parts 13 as shown in FIG. 4. It is desirable that a radius curvature R of the corner parts 13 is not more than 0.1 mm at an outer surface. The corner parts 13 in the cross sectional shape of the wire material 11 is six or less, i.e., the cross sectional shape of the wire material 11 is a hexagon or less, so that the wire material 11 has a large gentle bend surface with the radius curvature 2.5 mm or larger; as a result, it is possible to enlarge a contact area of the materials for metal porous body 10 are in contact with each other, and a bonded part between the material for metal porous body 10 when the metal porous body 101 is manufactured.

(16) The material for metal porous body 10 in the present embodiment is not a perfect coil shape, but formed to be twisted as a whole. The cross sectional shape of the wire material 11 is not limited to an even and same shape over a whole length. Therefore, as shown in FIG. 3, the cross sectional shape and a section area S of the wire material 11 may be different in accordance with a position of the length direction (an axis direction of the material for metal porous body 10.

(17) Since the cross sectional shape and the section area S of the wire material 11 are different in accordance with a measured position, in the present embodiment, an equivalent circle diameter (which is a diameter of a circle having the same area as the section area S) is calculated from the section area S of the wire material 11 at prescribed position, and this value is considered as a wire diameter at this position. Evaluation of the wire material 11 is carried out by an average value of the wire diameters (an average wire diameter Dw) measured at prescribed positions (e.g., ten positions) of the material for metal porous body 10.

(18) It is preferable that the average wire diameter Dw of the wire material 11 be not less than 0.05 mm and not more than 2.00 mm. If the average wire diameter Dw is 0.1 mm or larger, the coil shape can be easily formed and the productivity of the material for metal porous body 10 is high. Accordingly, the average wire diameter Dw is preferably 0.1 mm or larger. If the average wire diameter Dw of the wire material 11 is less than 0.05 mm, since the wire material 11 is thin and the manufacturing difficulty of the coil shape is high and it is not suitable for mass production.

(19) If the average wire diameter Dw of the wire material 11 is more than 2.00 mm, an interval G between the materials for metal porous body 10 in contact with each other tends to large when the materials for metal porous body 10 are stacked as schematically shown in FIG. 5. As a result, it is concerned that a porosity of the metal porous body 101 is far from an assumption from a porosity Q (mentioned later) of the material for metal porous body 10, and the porosity cannot be stably controlled.

(20) As shown in FIG. 1, The material for metal porous body 10 made of the wire material 11 described above has a plurality of coil parts 12. Where a number (a winding number) of the coil parts 12 is N, the winding number N in the material for metal porous body 10 is 1 to 10 inclusive. In FIG. 1, the material for metal porous body 10 is provided with the coil parts 12 of a length of 2.5 wounds (N=2.5). If the winding number N is less than 1, it is hard to obtain a three-dimensional coil shape, so that it is difficult to maintain a sufficient pore size and the porosity when arranging the material for metal porous body 10. If the winding number N is more than 10, the manufacturing difficulty of the coil shape is high, so that the manufacturing cost is high and it is not suitable for the mass production.

(21) A length L (mm) of the whole material for metal porous body 10 is preferably not less than 1 mm and not more than 20 mm. The coil length L is too short if it is less than 1 mm: it is difficult to convey the material for metal porous body 10 with stably maintaining the posture (a position and a direction) when conveying by a feeder and the like. If the coil length L is more than 20 mm, the position and the direction of the material for metal porous body 10 are unstable while conveying, and it is difficult to convey the material for metal porous body 10 with stably maintaining the posture.

(22) Since it is difficult to measure an outer diameter D of each of the coil parts 12 as a circular outer diameter, the coil outer diameter D of the coil parts 12 is a dimension which can obtained by two points positioned outermost in about one winding of the coil parts 12 opposing with 180° measuring in a direction perpendicular to the length direction of the coil parts 12. An average coil outer diameter Dc is a value dividing a total sum of the outer diameter D of the coil parts 12 by the winding number N.

(23) The average coil outer diameter Dc (mm) of the material for metal porous body 10 is preferably formed to be not less than 0.5 mm and not more than 10.0 mm. If the average coil outer diameter Dc is less than 0.5 mm, it is difficult to hold the material for metal porous body 10 by a robotic arm and the like when treating it, so that it is hard to arrange it in an intended position and direction. If the average coil outer diameter Dc is more than 10.0 mm, the interval G between the materials for metal porous body 10 being in contact with each other tends to be large when the materials for metal porous body 10 are aligned (refer to FIG. 5). As a result, it is concerned that the porosity of the metal porous body 101 is far from an assumption from the porosity Q of the material for metal porous body 10, and the porosity cannot be stably controlled.

(24) As described above, since the material for metal porous body 10 is formed to be twisted as a whole, the coil outer diameter D of the coil parts 12 is easily formed to have different sizes between one end and the other end. However, because the material for metal porous body 10 has the average coil outer diameter Dc is in the above range 0.5 mm to 10.0 mm inclusive, it is possible to form the shape of the average coil parts 12 to be a suitable size for controlling the interval G considering handling property and the arrangement.

(25) The coil parts 12 are included in embodiments of the present invention if the shape thereof is formed not only in a strict circle shape, but also various shapes such as an oval, a polygon, and the like. The axis direction through the centers of the coil parts 12 may be a straight as shown in the axis D in FIG. 1, or may be a curved axis such as an are shape. A winding direction of the coil parts 12 may be one as a right direction or a left direction, or may be changed in a middle of the direction of the coil length L.

(26) An aspect ratio (L/Dc) of the average coil outer diameter Dc and the coil length L is preferably not less than 0.1 and not more than 10.0. If the aspect ratio (L/DC) is less than 0.1 or more than 10.0, it may be difficult to stably arrange the material for metal porous body 10 depending on the position and the direction. As a result, it is difficult to manufacture the metal porous body 101 having desired directionality.

(27) As shown in FIG. 1 and FIG. 3, it is preferable that a pitch ratio (P/Dw) of a pitch P and the average wire diameter Dw be not less than 1 and not more than 50, where the pitch P is an interval between turns in a direction of the coil length L in the material for metal porous body 10. Although the most coil parts 12 have the different pitches P respectively, it is preferable that the pitch ratio (P/Dw) be not less than 1 and not more than 50 in each of the coil parts 12.

(28) If the pitch ratio (P/Dw) is less than one, the pitch P is smaller than the average wire diameter Dw and opening of the coil shape of the material for metal porous body 10 is too small. As a result, the materials for metal porous body 10 are less entangled when combined. Accordingly, when the metal porous body 101 is manufactured, there are few joined portions of the materials for metal porous body 10 with each other and the strength is low, so that stability of the shape may be deteriorated.

(29) If the pitch ratio (P/Dw) is more than 50, the pitch P is too large, so that the coil shape of the other material for a metal porous material 10 easily enters in the coil shape of the material for metal porous body 10. As a result, it is concerned that the porosity of the metal porous body 101 is far from an assumption from the porosity of the material for metal porous body 10, and the porosity cannot be stably controlled.

(30) As shown in FIG. 6, it is preferable that in a state in which one end 14a thereof along a direction following the coil length L is supported in a cantilever manner and the other end 14b is deflected with a deflection amount δ (mm) by an own weight, a deflection ratio (δ/L) of the coil length L and the deflection amount δ be not more than 0.20. If the deflection ratio (δ/L) is more than 0.20 (20%), it is easy to be deformed when handled by a robotic arm and the like.

(31) The porosity Q of the material for metal porous body 10 is calculated as follows. First, an occupied volume Vc (mm.sup.3) and a material volume Vw (mm.sup.3) of the material for metal porous body 10 are respectively calculated as follows;
Vc=L×π×(Dc/2).sup.2
Vw=[π×(Dw/2).sup.2]×(Dc−Dw)×π×N
where the coil length is L, the coil winding number is N, and the average coil outer diameter is Dc in the material for metal porous body 10; and the average wire diameter is Dw in the wire material 11.

(32) The porosity Q of the material for a porous body 10 is calculated as follows, from the occupied volume Vc and the material volume Vw calculated as above;
Q=(1−Vw/Vc)×100
The porosity Q of the material for metal porous body 10 is preferably not less than 30.0% and not more than 99.9%.

(33) In a case in which the porosity Q of the material for metal porous body 10 is set to be smaller than 30.0%, inside of the coil shape (an inner diameter of the coil) is small. Accordingly, it is difficult to manufacture the metal porous body 10 having a sufficient space. If the porosity Q is larger than 99.9%, the strength of the material for metal porous body 10 is deteriorated, and it is concerned to be broken while conveying by the feeder and the like.

(34) For the wire material 11 forming the material for metal porous body 10, a wire-string material and cut pieces generated by cutting machining by milling machine and the like can be used. The wire-string material may form a cross sectional shape other than a circle by a draw die.

(35) Photographs of the material for metal porous body 10 made of the cut piece is shown in FIG. 7 and FIG. 8. FIG. 7 shows the whole of the material for metal porous body 10. FIG. 8 shows a cross sectional shape of the material for metal porous body 10. The material for metal porous body 10 made of the cut piece can be formed with specifying the cross sectional shape (a lateral cross section) of the wire material 11 by a form of a cutting edge of a cutting tool, especially a form of a flank of the cutting edge, cutting property of a cut work, cutting condition and the like. However, the cross sectional shape is not constant.

(36) The cross sectional shape of the wire material 11 is not limited to a circle and the like which can be obtained by minutely machining and may be undefined forms having the plurality of corner parts 13 as in this material for metal porous body 10. In this case, in the cross section of the wire material 11, the surfaces between the corner parts 13 may be formed of flat surfaces, curved surfaces, and slightly uneven curved surfaces and the like: it is a polygon having six or less corner parts 13 as a whole.

(37) —Structure of Metal Porous Body—

(38) Next, the metal porous body 101 (FIG. 9) consisting of the materials for metal porous body 10 formed as above will be explained. The metal porous body 101 is formed by combining and sintering the plurality of materials for metal porous body 10 as shown in FIG. 9.

(39) In order to manufacturing the metal porous body 101 shown in FIG. 9, for example in a case in which the materials for metal porous body 10 are aluminum, by a mold or the like (not illustrated), the plurality of materials for metal porous body 10 are aligned in one row at the same posture with the coil length L direction (the axis direction) are together, and so that a plurality of rows are aligned in parallel so as to arrange them in flat. The rows may be sterically stacked in a height direction.

(40) At this time, since the materials for metal porous body 10 are formed in the coil shape, it is easy to handle them. Accordingly, without careful attention, the plurality of materials for a porous metal body 10 can be arranged, stacked and fill at any position and in any direction by a feeder, a robotic arm, and the like. As a result, it is easy to control the distribution of the materials for metal porous body 10 in the mold.

(41) Although omitting illustrations, specifically, the material for metal porous body 10 can be relatively conveyed easily by equipment for feeding parts (a part feeder). Since the material for metal porous body 10 is formed in the coil shape, although the materials for metal porous body 10 are concerned to be entangled, these are respectively picked out easily by using a standard disentangling device for springs.

(42) In the parts feeder, the materials for metal porous body 10 are conveyed through a round conveying path, and aligned in a prescribed direction while conveying. Accordingly, by storing the materials for metal porous body 10 fed from the part feeder with aligning in a line, it is possible to maintain the certain posture of the materials for metal porous body 10 and to handle the materials for metal porous body 10 easily.

(43) As described above, after filling the mold with the materials for metal porous body 10 by the feeder or the robotic arm, the materials for metal porous body 10 stuffed in the mold are heated, for example, at 600° C. for 0.5 to 60 minutes in an inert atmosphere. Thereby, contact parts between the materials for metal porous body 10 are sintered, the metal porous body 101 in which the materials for metal porous body 10 are integrally bonded with sintered parts (metallurgically bonded parts) therebetween is manufactured.

(44) The materials for metal porous body 10 may be bonded by bonding material such as solder or the like. In a case in which the materials for metal porous body 10 are made of metal material having good sinterability such as aluminum, aluminum alloy, copper, copper alloy or the like, it is possible to sinter the materials for metal porous body 10 without additive assisting in sintering. In order to improve the sinterability, powder of magnesium or silicon may be adhered by binders. In the embodiment of the present invention, the sintered parts, the solder bonded parts, and the like are called metallurgically bonded parts.

(45) In the metal porous body 101 formed as above described, since the plurality of materials for metal porous body 10 are arranged at the same posture in the direction of the coil length L, pores having directionality along the direction of the coil length L are formed. By combining the plurality of the materials for metal porous body 10 formed in the coil shape, it is easy to manufacture the metal porous body 101 having the anisotropy (directionality). Since it is possible to freely control the porosity and the like only by changing the average wire diameter Dw and the like of the wire material 10 of the material for metal porous body 10 forming the metal porous body 101, flexibility of product design is high.

(46) In the metal porous body 101, since the materials for metal porous body 10 are bonded by the sintered parts therebetween, thermal stress at bonding boundary surfaces is small and the heat can smoothly moves between the materials for metal porous body 10. Since the spaces (the pores) are formed inside the materials for metal porous body 10 which are formed into the coil shape, the heat medium can flow through the spaces and liquid can be impregnated here. By combining the materials for metal porous body 10 formed in the coil shape, it is possible to control the porosity, the pore size, mechanical characteristics, thermal characteristics, sound absorption characteristics, fluid passing characteristics, liquid impregnation characteristics and the like of the metal porous body 101.

(47) In the above embodiment, the metal porous body 101 having the anisotropy (the directionality) is explained. However, as shown in FIG. 10, by arranging and combining the materials for metal porous body 10 in different directions, a metal porous body 102 having isotropy (without the directionality) can be easily formed. As shown in FIG. 11, by combining the coil-shaped materials for metal porous body 10, a metal porous body 103 can be easily formed to have lopsidedness in a direction of flow of the fluid. In the metal porous body 103 shown in FIG. 11, the lopsidedness is given by arranging the axis of the coil in the material for metal porous body 10 to be a lateral direction to a vertical direction from an upper to lower of the drawing.

(48) The present invention is not limited to the above-described embodiments and various modifications may be made without departing from the scope of the present invention.

Examples

(49) As Examples of the present invention, the followings were made:

(50) (1) Samples Nos. 1 to 12 of the metal porous body using the materials for metal porous body made of wire material made of aluminum; and

(51) (2) Samples Nos. 13 to 15 of the metal porous body using the materials for metal porous body made of aluminum made by cutting machining.

(52) Conditions, such as dimensions, of the material for metal porous body and the metal porous body are shown in Table 1 and Table 2.

(53) Each of the metal porous bodies was formed by arranging the materials for metal porous body to have the isotropy so that the axis direction of the coils are alternate in the vertical direction and the lateral direction (refer to FIG. 10), in a size of vertical 50 mm×lateral 30 mm×height 30 mm. The cross sectional shape (the cross section) of Samples Nos. 1 to 12 of the material for metal porous body (the wire material) made of the wire string material is a circle. The cross sectional shape of Samples Nos. 13 to 15 of the material for metal porous body (the wire material) made by the cutting machining is a triangle.

(54) TABLE-US-00001 TABLE 1 Coil Length Average Coil Outer Average Wire Winding Sample No. L (mm) Diameter Dc (mm) Diameter Dw (mm) Number N (1) 1 5 5 0.35 4 2 10 5 0.35 6 3 7.5 5 0.2 5.5 4 10 5 0.5 7 5 10 5 0.5 5 6 10 5 0.5 8 7 5 5 0.35 4 8 10 5 0.35 6 9 7.5 5 0.2 5.5 10 10 5 0.5 7 11 10 5 0.5 5 12 10 5 0.5 8 (2) 13 8.7 3.1 0.28 1.5 14 7.8 2.3 0.29 1.4 15 8.5 2.7 0.2 1.5

(55) TABLE-US-00002 TABLE 2 Porosity Q (%) Porosity (%) of Material for Aspect Ratio Pitch Ratio of Metal Porous Sample No. Metal Porous Body (L/Dc) (P/Dw) Material (1) 1 94.3 1 3.6 99.5 2 95.7 2 4.8 99.6 3 98.2 1.5 6.8 99.7 4 90.1 2 2.9 99.4 5 92.9 2 4.0 99.5 6 88.7 2 2.5 99.2 7 94.3 1 3.6 93.3 8 95.7 2 4.8 95.2 9 98.2 1.5 6.8 96.7 10 90.1 2 2.9 92.3 11 92.9 2 4.0 93.4 12 88.7 2 2.5 90.6 (2) 13 98.8 2.8 20.7 85.1 14 98.2 3.4 19.2 77.9 15 99.2 3.1 28.3 90.4

(56) As shown in Table 1 and Table 2, by combining the coil-shape materials for metal porous body, the metal porous body was able to be formed to have the prescribed porosity.

(57) Next, using the material for metal porous body of Sample No. 13, Samples Nos. 21 to 23 of the metal porous bodies in which the directionality of the pores were controlled were made. The metal porous bodies of Nos. 21 to 23 were made to have a size vertical 38 mm×lateral 55 mm×height 6 mm and a porosity 90%.

(58) In the metal porous body of Sample No. 21, the materials for metal porous body were arranged so that the axis direction (the direction of the coil length L) of the coil to be parallel to the lateral direction (55 mm) so that the metal porous body had a lateral directionality. In the metal porous body of Sample No. 22, the materials for metal porous body were arranged so that the axis direction of the coil to be parallel to the vertical direction (38 mm) so that the metal porous body had a vertical directionality. The metal porous body of Sample No. 23, the materials for metal porous body were arranged so that the axis direction of the coil to be alternate of the vertical direction and the lateral direction (refer to FIG. 10), so that the metal porous body had isotropy.

(59) For these metal porous bodies of Sample Nos. 21 to 23, pressure loss was measured when water flowed from one end surface to the other end surface of 38 mm×6 mm (in the lateral direction). The measurements of the pressure loss were carried out with flow rates of water entered from the one end surface as 2.1 (m/s) and 4.3 (m/s). The pressure loss (kPa) was measured as a pressure difference between a pressure at the entering one end surface and a pressure at the exiting other end surface. The results are shown in Table 3.

(60) TABLE-US-00003 TABLE 3 Pressure Loss (kPa) Sample No. 2.1 (m/s) 4.3 (m/s) 21 0.14 0.46 22 0.31 1.02 23 0.23 0.75

(61) As known from the results of Table 3, the pressure loss in No. 21 was the smallest in the three because the materials for metal porous body were arranged so that the axis direction of was the same direction as the flow of water (the lateral direction). The pressure loss in No. 22 was the largest in the three because the axis direction of the materials for metal porous body was perpendicular to the flow direction of the water (the vertical direction). The pressure loss in No. 23 was a medium value between No. 21 and No. 22 because the axis directions of the materials for metal porous body were random by mixing of the vertical direction and the lateral direction. As recognized from these results, by the plurality of materials for metal porous body combined so that the arrangements thereof are different, the metal porous bodies having different orientations (the directionality of a fluid flowing) can be formed.

INDUSTRIAL APPLICABILITY

(62) The material for metal porous body having various purposes can be provided and the directionality of the metal porous body (isotropy, anisotropy, and the lopsidedness) can be easily controlled.

REFERENCE SIGNS LIST

(63) 10 Material for metal porous body 11 Wire material 12 Coil part 13 Corner part 14a One end 14b Other end 101, 102, 103 Metal porous body G Interval R Radius curvature S Section area δ Deflection amount