Preparation of W-Y2O3 Alloy by Wet Chemical Process with Ammonium Paratungstate

Tungsten is a heavy metal exhibits the highest melting point among all the refractory metals. The pure tungsten has a yield strength of 750 MPa and excellent tensile strength of 900 MPa. Due to its amazing strength and hardness, tungsten was widely applied in various fields include defense industry, aerospace industry, and nuclear industry. The conventional alloying method by combining tungsten with other metals is a proven efficient route to enhance its properties to extend its applications.

Moreover, rare earth oxides had been reported to be combined with tungsten alloys and had been to achieve enhanced performance. To enhance the physical properties of tungsten alloys, rare earth oxide Yttrium oxide (Y2O3) was doped with W to prepare composite powders. an improved wet chemical method and spark plasma sintering (SPS) were utilized to synthesize ultrafine W-Y2O3 composite powders. Smaller grain size and higher relative density were obtained.

The preparation method of W-Y2O3 alloy by wet chemical process using ammonium paratungstate as raw material is as below:

Ammonium paratungstate (APT) and yttrium nitrate hydrate (YN3O9·6H2O) were used without further treatment. Firstly, 2 g of anionic surfactant SDS and 2.57 g of yttrium nitrate hydrate were dissolved in 120 ml of water. Then 20 g of APT was added into the transparent solution. After mechanical stirring and ultrasonic treatment for 10 min, 20 ml of nitric acid (65%–68%) was added into the solution and left to react for 30 min. After that, 140 ml of ethanol was added into the formed suspension. After further reaction for 3 h, the suspension was filtered. Mechanical stirring and ultrasonic treatment were carried out throughout the whole process. The collected precipitate was washed with ethanol for four times and left to dry in vacuum drying oven at 60 °C for 24 h.

Using a temperature profile including three isothermal steps (450 °C for 1 h, 600 °C for 3 h, and 800 °C for 6 h), thermal processing (calcination and reduction) of the composite powders was carried out in a tube furnace. The ramping rate was 5 °C·min− 1. Argon gas was passed through the furnace from room temperature to the end of isothermal stage at 450 °C, followed by reduction with hydrogen gas. Then the composite powders were left in furnace to cool down to room temperature under hydrogen atmosphere.

In conclusion, W-Y2O3 alloy was prepared by wet chemical process using ammonium paratungstate as raw material.  Average grain size of 40–50 nm was obtained for the composite powders and smaller grain size of about 700 nm and high density were achieved for sintered alloys. higher relative density as 99.0% was also achieved by mechanical milling.

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