Sintering mould

Abstract

The invention provides a sintering mould. The sintering mould comprises an outer sleeve, a bottom cover, a top cover, an upper mould, a lower mould, a lower graphite rod and an upper graphite rod, wherein the bottom cover and the top cover are respectively arranged at the bottom and the top of the outer sleeve; the lower mould is placed in a hollow cavity arranged on the outer sleeve and is placed on the bottom cover; the lower part of the upper mould is sleeved at the outer side of the lower mould and the lower graphite rod is inserted into a hollow cavity arranged in the lower mould; and the upper graphite rod is inserted into a hollow cavity arranged in the upper mould and is placed at the top of the lower graphite rod. The three components including the outer sleeve, the bottom cover and the top cover are in a separated design so that the loading of a sample and the replacing of a graphite mould are very easy. A cylindrical protection sleeve of the outer sleeve has the function of preventing from oxidizing the graphite mould at a high temperature, and also increases the compression strength of the graphite mould so as to improve the compression capability is improved by at least 1.5 times. The sample can be more easily taken out through a tapered round table design of the lower mould. When the sintering mould is used at the high temperature, a vacuum cavity does not need to be additionally arranged, a mould unloading process does not need to be forcedly processed, and the sample integrity is 100%, so that the service life of graphite is prolonged.

Description

technical field [0001] The invention relates to a sintering mould, which belongs to the modification technology of the sintering mould. Background technique [0002] In the field of special ceramics and thermoelectric bulk materials, ultra-high temperature and rapid sintering of nanostructure samples is often required. The molds of these high-temperature sintered samples often use graphite molds with high melting point and small expansion coefficient (the melting point of graphite is above 3500°C). Its typical structure is as figure 1 As shown, the main body is cylindrical, and the powder sample is placed in the inner circular cavity. When pressing the sample, graphite rods are placed at both ends of the powder sample to apply pressure. sample. The use of such graphite molds has the following problems: (1) It is necessary to add some additional vacuum chambers to prevent them from being oxidized at high temperatures, which increases equipment costs and use costs; (2) The ...

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Problems solved by technology

The use of such graphite molds has the following problems: (1) It is necessary to add some additional vacuum chambers to prevent them from being oxidized at high temperatures, which increases equipment costs and use costs; (2) The pressure resistance of graphite molds is relatively poor, and imported molds The maximum withstand pressure of graphite is usually lower than 80MPa. When the sample is withdrawn from the mold after sintering, the graphite mold is easy to crack; (3) the current graphite molds are all cylindrical

Although the coefficient of thermal expansion of graphite is at least 10 smaller than that of metal 6 order of magnitude, but some samples themselves shrink when heated and expand when cooled, and are tightly squeezed into the mold after cooling down from high temperature. If they are forced out, the samples are often crushed

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