How Scientists Make Some Metallic Materials Sweat Short 5

It is a kind of biomimetic technology, which is successfully developed by using the instinct of organisms to adjust their own environment (temperature) in order to survive.

This is my own suggestion, hopefully (o) oh.

Sweating cooling material is a kind of metal material that can "sweat", this metal material still has good mechanical properties and physical and chemical properties when used in ultra-high temperature working environment, so as to meet the requirements of high temperature working parts.

After the Second World War, with the development of aerospace technology, the requirements for the various properties of the required materials, especially the materials of high-temperature working parts, are getting higher and higher. In the aerospace field, the working temperature of some materials far exceeds the melting point of the material (nearly 3000), and its relevant properties are required to remain at a certain level. This kind of working parts, the material under the general convention is not able to meet the requirements.

In order to solve the urgent need of the country for materials, in addition to the development of new high-temperature special materials, since the early sixties of the last century, the corresponding cooling technology has been studied on the materials to improve the use temperature of materials. For example, convection cooling and air film cooling can greatly increase the use temperature of materials, but they are far from meeting the needs of aerospace technology. After nearly 20 years of research and development, the sweat cooling technology satisfactorily solved the demand for aerospace materials at the end of the 70s of the last century.

Metallic sweating materials must be composed of a high melting point metal with certain strength and high temperature resistance and a low melting point metal with a large latent heat of melting and evaporation. The two metals should neither be soluble with each other nor form intermetallic compounds, but form their own independent uniform two-phase structure. High-melting metals form a porous skeleton with evenly spaced and connected pores to allow for filling with low-melting metals.

Therefore, the properties of metal sweating materials are determined by the characteristics of the two metals, the particle size and shape of the original powder, the density and strength of the skeleton, the shape, size and distribution of the pores, the volume percentage of the pores and the metal content with low melting point. Commonly used metals with high melting points are tungsten and molybdenum; Thorium tungsten and tungsten carbide (WC) can also be used instead of tungsten as high melting point components.

In addition to silver and copper, silver-copper alloys, tin, lead, zinc, magnesium, AG-15 N, etc. have also been used in low-melting point metals. Typical tungsten silver sweat material (W-10AG) has the following properties: density; The tensile strength at 20 and 1093 temperatures is 56 and 21 kgf mm, and the yield strength is 42 and 16 kgf mm, respectively; Modulus of elasticity at room temperature: 29400kgf mm; And it has good resistance to high temperature ablation, thermal shock and machinability.

The performance of the W-10CU is similar.