Gas sensing at room temperature has attracted a lot of research interest, especially the combination of MOX, CNT and graphene, but it usually has the problems of slow response time, poor baseline stability, and high humidity dependence.

Cemented carbide or tungsten carbide (W2C) is widely used in cutting tools, drilling tools and wear-resistant tools due to its excellent tensile strength, fracture toughness, thermal shock resistance and hardness. By reducing the grain size of WC or adding appropriate reinforcing materials, the mechanical properties of cemented carbide can be greatly improved. The grain size of WC can be suppressed by adding a grain inhibitor or using low-temperature rapid sintering.

High-performance gas sensors are receiving more and more attention due to their wide application in pollutant detection, medical diagnosis, chemical monitoring, food processing and other fields. Tungsten oxide (WOx) has received considerable attention as a promising sensing material due to its high sensitivity and stability, specifically towards hydrogen sulfide (H2S) gas. Various WO3 nanostructures such as nanoparticles, nanowhisker, nanorods, and nanowires have shown enhanced sensing properties towards different gases.

Ammonium paratungstate (APT) is a known intermediate to produce metallic tungsten, tungsten-containing catalysts, or tungsten-based hard materials (such as tungsten carbide) or sputtering targets. The latter application requires particularly high purity APT. There are two major source of tungsten which include tungsten ores and recycle of tungsten scraps.