SU1038066A1 - Method of producing sintered articles of covar - Google Patents

Abstract

THE METHOD OF MANUFACTURING SINTER} FROM THE CARPET, including powder grinding, pressing and sintering, is distinguished by the fact that: In order to increase the process performance and density of the products, the powder is ground before grinding to -L80-90 Pc and held for 1 -2 h, and after grinding, annealed at BOO-bbO C for 1-2 h. (L with

Description

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The invention relates to powder metallurgy, in particular, to methods for the manufacture of parts for electrovacuum devices from covar powder. The method can be used in the engineering industry. where materials with a thermal expansion coefficient equal to the thermal expansion coefficient of the glass are required.

A known method for the manufacture of kovara by co-reduction of the initial powders of iron oxides, cobalt and nickel, followed by pressing, sintering and additional compaction of l. .15

However, this method does not ensure the production of products with stable physicomechanical properties due to the presence of impurities (oxides and chlorides), and also does not allow the use of metal cutting and forge production as a source of raw materials.

Closest to the present invention is a method for manufacturing powder products, including grinding of pores, sheathing, pressing and sintering .2j.

The disadvantage of the known method is low productivity due to the duration of the process of extracting the powar powders, which are 9–4. with very plate. Thus, for example, when grinding a powder of a spray-dried covar for 2k hours in an attritor, the powder particles are practically not crushed. The duration of grinding of such powders reaches several days, which significantly reduces the efficiency of the powder metallurgy process. In addition, after grinding, such powders are so sticky that pressing them without the use of a plasticizer is almost impossible. As a result, the density of the compacts is in the range of 52-60 from the theoretical.

The purpose of the method is to increase the performance of the process and the density of products.

This goal is achieved according to 50 "the method of making sintered Kovar products, including grinding of the powder, pressing and sintering, the powder of the kovar is cooled to - (80-90) ° С before grinding, and allowed to stand for 1-2 hours after grinding annealed at 600-b50 ° C gr for 1-2 hours

The cooling of the kovar powder to a temperature of less than or equal to -80 ° C is necessary for the transformation of the α phase to a more brittle about α phase, which is better ground. The temperature is equal to.

Cooling to a temperature higher will lead to incomplete jf-O-transformation, which will reduce the productivity of the process of manufacturing products.

Cooling to a temperature below does not lead to a noticeable increase in the productivity of the process of manufacturing products, since CX transformation already occurs at -80 ° C.

Exposure of the powder for 1-2 hours provides the most complete conversion. With a shutter speed of less than 1 hour, a sufficiently complete y — o occurs (transformation, as a result, the grinding time increases, which leads to a decrease in the productivity of manufacturing products. Exposure is longer than 2 hours; it is impractical because almost full V -o the transformation.

Annealing the powder at a temperature of 600gb50 ° C is necessary to remove the work hardening after grinding and eliminate the mixing operation with the plasticizer. Annealing at temperatures below does not provide a sufficiently complete removal of the work hardening. As a result, the density of the compacts is reduced. Annealing at a temperature higher causes the particles to set together, which requires an additional grinding operation. The annealing time is selected at the rate of the most complete removal, work hardening. With a dwell time of less than 1 hour, sufficient hardening is not sufficiently removed, which reduces the density of the compacts. Exposure for more than 2 hours reduces the productivity of the manufacturing process.

The method is carried out as follows.

Kovar powder obtained by spraying or Kovar waste from the metal-working industry is cooled to a temperature equal to or less than -80 ° C and held for 1-2 hours. Then the powder is milled to the required particle size. After which the powder is annealed in a reducing atmosphere (for example, dissociated ammonia) at 600-650 C for 1-2 and pressed at a pressure of 400-700 MPa. The resulting compact is sintered in a protective atmosphere at 1270-1300 ° C. Example 1. Kovar powder obtained by spraying is cooled to a temperature of -80 ° C and held for 2 hours, milled in an attritor for 23 hours and a powder with a particle size of not more than 56 microns is obtained. The ground powder is annealed at 600 ° C in an atmosphere of dissociated ammonia for 1 hour. The powder is pressed into blank blanks for a large integrated circuit at a pressure of 550 MPa. The relative density of the compact is 80. Then the blanks are sintered at 128 ° F in a dissociated ammonia atmosphere for 1 m. As a result, a frame was obtained with the following dimensions: height 1 mm, length 9 mm, width b mm, wall thickness 0, The time of making one frame was 0 ,. PRI me R., Analogously to example 1, make the frame. The Kovar powder, cooled to 1, is kept for 1 hour and milled in the attritor for 26 hours (particle size does not exceed 5 µm), annealed at 650 C for 2 m, pressed at pressures of 550 MPa (relative density of the press is 82) and sintered at 1280 ° C in an atmosphere of dissociated ammonia for 1 h. The time of manufacture of one part was 0.8 min. Example 3. The metal-working industry waste (chips) is cooled before and held for 1.5 hours. Then the chips are ground in an attritor for 23 hours (particle size does not exceed 5b microns), annealed in an atmosphere of dissociated ammonia for about 1.5 hours. m, pressed at a pressure of t55 O MPa (relative density of 31%) and sintered at 1280 C in an atmosphere of dissociated ammonia for 1 h. As a result, the frame of the Large Integrated Circuit was obtained. The time of manufacture of one frame was. Oh, 7 min. The frame of the large integrated circuit was manufactured in a known manner. At the same time, the grinding time to a particle size of not more than 56 µm was 9b hours. The relative density of the compacts was 52%. The production time of one frame was 2 minutes. As can be seen from examples 1-3, the production time of one frame according to the proposed method is 0-, 60, 8 minutes, and the relative density of compacts is 80-82%, while the time of production of one part by a known method is 2 minutes, the relative density of the press. 52%. Thus, the proposed manufacturing of products from Kovar powder, in comparison with the known, allows to increase the productivity of the process and allows to increase the utilization rate of the metal to 0.95.

Claims (1)

METHOD FOR PRODUCING SINTERED * PRODUCTS FROM CARPET, including grinding the powder, pressing and sintering, distinguished by the fact that, in order to increase the productivity of the process and the density of the products, the powder is cooled to - (30-9 (^ 0 and incubated for 1-2 hours, and after grinding annealed at 6OO-65O ° C for 1-2 hours 9908i (P ' ^{_, go_} P§ 1 1038066