Quick microwave synthesizing-sintering preparation method of ZrNiSn bulk thermoelectric material

Abstract

The invention discloses a quick microwave synthesizing-sintering preparation method of a ZrNiSn bulk thermoelectric material and belongs to the technical field of thermoelectric material preparation methods. The quick microwave synthesizing-sintering preparation method of the ZrNiSn bulk thermoelectric material comprises the following steps: preparation and cold-pressing forming of raw materials, microwave synthesis, crushing, ball milling and secondary cold-pressing forming of ZrNiSn thermoelectric alloy, and microwave sintering. According to the method, microwave synthesis and microwave sintering are combined, and various processing parameters in the synthesizing and sintering processes are controlled, so that in-situ nano-crystals precipitation from tissues of the ZrNiSn thermoelectric material is realized, accordingly, the thermal conductivity of the ZrNiSn thermoelectric material is remarkably reduced, and the single-phase ZrNiSn bulk thermoelectric material with superior thermoelectric property and uniform tissue and performance distribution is obtained.

Description

technical field [0001] The invention belongs to the technical field of thermoelectric material preparation methods, and more specifically relates to a microwave rapid synthesis-sintering method for preparing ZrNiSn block thermoelectric materials. Background technique [0002] Thermoelectric material is a functional material that uses the movement of carriers inside a solid to realize direct mutual conversion of thermal energy and electrical energy. Due to its small size, light weight, and no noise during operation, thermoelectric devices will not cause any environmental pollution and have a long service life. And other advantages, so it has a wide range of applications in thermoelectric power generation and thermoelectric refrigeration. The thermoelectric performance of thermoelectric materials is generally measured by the dimensionless thermoelectric figure of merit (ZT). where S is the Seebeck coefficient, ρ is the electrical resistivity, κ is the thermal conductivity, a...

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Problems solved by technology

When the solid-state reaction method is used to synthesize ZrNiSn thermoelectric materials, in order to fully react the components, the reaction time generally needs to last for several days or even two weeks, the preparation period is too long and the cost is too high

However, when mechanical alloying is used for synthesis, ZrNiSn alloys with a single crystal phase cannot be effectively synthesized.

In the sintering stage, hot pressing sintering and spark plasma sintering are the two most widely used sintering methods. Although they can effectively improve the density of bulk ZrNiSn alloy materials and ensure the electrical properties of the material to a certain extent, the prepared bulk ZrNiSn alloy materials The thermal conductivity of bulk ZrNiSn alloy materials is high (generally 6-10Wm -1 K -1 ), in order to reduce its thermal conductivity, other complex processes need to be used, such as adding nanosecond equals during sintering, which greatly increases the cost

In addition, since the entire furnace body is heated during hot pressing sintering, the powder material is heated up by thermal radiation and convection, the heating rate is slow, and there is a temperature gradient in the material, resulting in uneven performance of the sintered body and affecting thermoelectric materials. normal use

The spark plasma sintering method generally adopts the heating method of switching pulse direct current, which requires a large current to directly heat the material itself for sintering. This method has high requirements for equipment and high equipment cost, which is difficult to meet the needs of industrial development.

[0005] Therefore, it is difficult to prepare a ZrNiSn bulk thermoelectric material with excellent thermoelectric performance, uniform structure and performance distribution, low preparation cost, and a single phase by using the usual synthesis and sintering methods of ZrNiSn thermoelectric materials in the prior art.

For example, Zhu Tiejun, Xiao Kai, etc. prepared doped ZrNiSn-based half-Heusler bulk thermoelectric materials by means of a combination of suspension smelting and spark plasma sintering (microstructure of ZrNiSn-based Half-Heusler thermoelectric materials prepared by rapid solidification method ), therefore, its synthesis effect on single-phase ZrNiSn is poor, so that its thermoelectric performance is affected, and the equipment cost is high

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