Ⅰ What is Tungsten Alloy?

There are two definitions of tungsten alloy: (1) tungsten alloy in a broad sense: metal materials containing tungsten are collectively called tungsten alloy, such as tungsten-iron alloy, tungsten-copper alloy, tungsten-nickel alloy and cemented carbide; (2) Tungsten alloy in a narrow sense: an alloy material composed of tungsten as a matrix material and a small amount of metal binders such as nickel, copper, iron, cobalt, molybdenum and chromium, also known as high specific gravity tungsten alloy or high density tungsten alloy or heavy alloy.

Tungsten Trioxide, also known as tungsten oxide (WO 3), has been widely used in many fields such as petrochemical industry, photoelectric information, national defense and military industry because of its special properties such as catalysis, optics and electricity.

Tungsten trioxide (WO 3), also known as yellow tungsten oxide, is an oxide of tungsten and an N-type semiconductor as well. These two characteristics make tungsten trioxide not only have high density, high boiling point and high melting point, but also have catalytic, optical and electrical properties.

Tungsten trioxide, also known as tungsten anhydride (WO₃), is a yellow powder, insoluble in water and alkali, and slightly soluble in acid. Because of its good optical, electrical and gas sensitive properties, it is widely used in life, chemical industry, medical treatment and military affairs.

WO3 has extremely high sensitivity for NO2 detection, and has been an ideal material for gas sensor coatings. WO3 has received considerable attention on the potential applications as gas sensors, photocatalyst and electrochromic devices. And it is also reported that doping another kind of oxides into WO3 leads to the formation of semiconductor heterojunction, thus can effectively improve the gas sensitivity of the coatings.

Tungsten is a metal with the highest melting point of 3440 °C.  Its excellent physical properties, such as good thermal conductivity and low thermal expansion coefficient, make it widely used in high-temperature applications, including aerospace, nuclear, and the national defence industry. One of the significant applications of tungsten is plasma-facing material, which faces a harsh environment such as high temperature, high nuclear irradiation.

The near-infrared radiation (NIR) absorbers are of fundamental significance in several fields of applications in optical sensors, photothermal energy converter, imaging, NIR stealth cloak, and smart windows.

Nitrogen dioxide (NO2) gas is a kind of toxic gas, which is mainly produced by the exhaust gas of burning fossil fuel. Breathing air with a high concentration of NO2 can irritate airways in the human respiratory system. It is reported that the short-term exposure limit of NO2 gas for human body is 1 ppm for 15 min. Thus, gas sensing detection of NO2 gas is very important to protect environment and protect human health. There are drawbacks of low sensing response and low decetion efficiency within common sensors.

Hydrogen energy is considered as the most promising renewable sources of energy to substitute fossil fuels. It has the advantages of zero-greenhouse emission, abundant resources, and high energy density. The electrocatalytic hydrogen evolution reaction (HER) using water splitting has received intense interest as an environmental-friendly technology consisting of HER and water oxidation reaction (WOR). Although the HER is a clean technology, it requires a high electric energy consumption and a high energetic efficiency. Thus, increasing the photocatalytic efficiency of HER is significantly necessary.

Ammonia (NH3) is a colorless and toxic gas, which has a pungent odor. which has a pungent odor. This compound has been widely used in agriculture, fertilizer, factories, food processing, power plants, refrigeration systems, medical treatments, and living environments. Inhalation of ammonia may cause various acute respiratory diseases. It is proved that exposure to ammonia above 50 ppm can irritate the eyes, nose, throat and skin, and extended exposure to ammonia above 200 ppm may even cause chemical burns of skin and permanent lung damage. Thus, the development of ammonia sensors is very significant in the applications of environmental monitoring, industrial process control, and food industry and medical diagnostics. The sensing materials of resistant-type ammonia sensors mainly include semiconducting metal oxides, carbon nanomaterials and conducting polymers.