Tungsten plate is a tungsten material pressed by special process, it is mainly used in electronics and semiconductor industry parts manufacturing, tungsten sputtering target, high temperature furnace with tungsten boat, sapphire long furnace components etc.
The conventional thin tungsten plate pressing process uses yellow tungsten oxide, because the size distribution of yellow oxide powder is narrow and the particle size of powder is uniform, the gap of particles is not easy to be filled in the process of pressing, which eventually leads to lower strength of pressing.
The physical and mechanical properties of the tungsten plate are closely related to the strength of the compact, the strength of compacts is related to the characteristics of tungsten powder morphology and particle size distribution. There are three types of commonly used tungsten trioxide, yellow tungsten oxide, blue tungsten oxide and purple tungsten oxide, its flagship product is divided into three level: ordinary, fine, superfine granularity. The three kinds of tungsten oxide are mixed in proportion, and the coarse and fine powder can complement each other, so as to achieve the ideal pressure intensity of the tungsten plate pressing.
BTO, VTO and YTO are mixed in a biconical mixer according to the ratio of 2 to 5: 10. After 2 hours, the three kinds of tungsten oxide mixture were used as raw materials, and they were laid in the boatpan and reduced in the reduction furnace. The material layer thickness is controlled between 10-12 mm, and the heating rate is 50°C/h. Hydrogen dew point is -70~-75°C. The five zone reduction temperature distribution is in the range of 700~950°C, and the residence time is 180 min in the high temperature zone. The fine powder will pass through the aperture 0.212 mm wire diameter 0.112 mm and the aperture 0.075 mm wire diameter 0.056 mm sieve twice. Finally, the high pressed compact powder was obtained.
Under the action of external loading, the powder with more fine particles is easier to self adjust, by moving, sliding and rotating, the gap between particles is easy to be filled, so that the large porosity in the blank is reduced. Due to the complex shape of the powder particles, the surface is rough, there is a part of the bridge between particles, forming a loose aggregation structure, which makes the powder clench in the pressing between the particles, so as to improve the strength of compacts, it is conducive to the preparation of high performance tungsten products.
Mix the yellow tungsten oxide, blue tungsten oxide and purple tungsten oxide three and proceed a reduction, it is a simple process, low energy consumption and good quality, no need to change the operation methods and processes, but the quality is already the best.