ABSTRACT

In order to prepare high-performance tungsten alloys, surface modification of tungsten nanopowders prepared by a wet chemical method was carried out by acid pickling at room temperature. The low-temperature sintering characteristics of tungsten nanpowders before and after pickling was compared and analysed. The surface modification was carried out by pickling with a solution of hydrofluoric acid, concentrated nitric acid and ammonium fluoride at room temperature. After this surface treatment, uniformly distributed step-shaped defects formed on the surface of the tungsten nanopowders. After low-temperature sintering, the grain size of the tungsten alloy corresponding to the surface-modified powder precursor was reduced by 20% compared to the alloy using untreated powder as precursor. In addition, the step-shaped defects also increase the sintering activity of the pickled tungsten powder and promote its sintering densification, making the final density of pure tungsten sintered at 1600°C as high as 96.7%, and its hardness greatly increased to 521 HV_0.2. The results show that room-temperature pickling and subsequent low-temperature sintering is a promising method for preparing high-performance nanotungsten alloys.

摘要

为了制备高性能的钨合金，在室温下通过酸洗对通过湿化学法制备的钨纳米粉进行表面改性。比较和分析了酸洗前后钨纳米粉的低温烧结特性。通过在室温下用氢氟酸，浓硝酸和氟化铵的溶液酸洗来进行表面改性。在该表面处理之后，在钨纳米粉的表面上形成均匀分布的台阶状缺陷。低温烧结后，与使用未经处理的粉末作为前体的合金相比，对应于表面改性粉末前体的钨合金的晶粒尺寸减小了20％。此外，_0.2。结果表明，室温酸洗和随后的低温烧结是制备高性能纳米钨合金的一种有前途的方法。