Compounds

Compounds are divided into organic compounds and inorganic compounds.

Organic compounds are compounds that contain carbon (but carbon-containing compounds are not necessarily organic). Compounds containing only carbon and hydrogen are called hydrocarbons. For example, methane (CH4) is an alkane, ethylene (C2H4) is an alkene, acetylene (C2H2) is an alkyne, and benzene (C6H6) is an aromatic hydrocarbon. Organic matter is a compound containing carbon (except CO2, CO, H2CO3 and carbonate) such as CH4, C2H5OH, CH3COOH all contain carbon (C) element.

Inorganic compounds do not contain hydrocarbons, such as H2O, KClO3, MnO2, KMnO4, NaOH, etc., are inorganic substances.

Metallic compounds

Metallic compounds and intermetallic compounds refer to compounds formed by metals and metals or metals and metalloids (such as H, B, N, S, P, C, Si, etc.). The applications of metals and intermetallic compounds are mainly as functional materials, shape memory materials and superconducting materials. The thermoelectric conversion functional material MoSi2 is not a typical intermetallic compound, but a sign from an intermetallic compound to a metal and nonmetal compound (silicon is not a metal but a semiconductor). Nevertheless, it is customary to classify silicon compounds as intermetallic compounds. Because it has many similarities with metals. There is also a main class of compounds formed by elements of Group IIIA and Group VA, such as InSb, GeAs, InAs, etc. The constituent elements of these phases include metals, semimetals and nonmetals, and the formed compounds are semiconductors, which do not belong to Intermetallic compounds with metallic properties.

At present, the main objects of our research are metal compounds and intermetallic compounds, which are an important part of many industrial and scientific research materials. Up to now, the wide range of applications and varieties are still in the field of functional materials with characteristics in optical, electrical, magnetic, superconducting and functional conversion.

For the preparation of metals and intermetallic compounds, we mainly use the following methods:

Self-spreading high temperature synthesis

Self-propagating high-temperature synthesis is a technique for synthesising materials using the self-heating and self-conducting effects of the reaction heat generated by a chemical reaction. Usually the reaction to argon or nitrogen as a protective atmosphere, ignition of the powder billet to produce a chemical reaction, the generation of heat so that the neighbouring powder temperature rises abruptly, triggering a chemical reaction, and in the form of a combustion wave spreads through the entire reaction, the combustion wave continues to implement the forward movement of the reactants into the end product.

Discharge plasma sintering

Discharge plasma sintering is the use of pulsed high current applied directly to the mould and the sample, thereby generating body heating, so that the sintered sample is rapidly warmed up, while the pulse current caused by the discharge effect between the particles, so that the particles of the local surface of the high temperature and melting, the surface of the material flaking, purified the surface of the particles, to achieve rapid sintering, and can effectively inhibit the particles to grow up.

Mechanical alloying

Mechanical alloying is a high-energy ball milling technique for the preparation of alloy powders, usually dry. Mutual collisions between the grinding balls and the powder cause flattening and work-hardening of the plastic powder, leading to particle overlap, surface contact and cold welding. The formation of multi-layer composite powder particles composed of various components, while the work hardening layer and composite particles fracture, cold welding and fracture constantly repeated, as well as sufficient kneading and mixing, so that the powder refinement and more uniform, and then the formation of prefabricated composite particles. Due to the large number of defects and nano-microstructure within the composite particles. Further high-energy ball milling occurs when the solid state reaction, the formation of new materials.

Directed Coagulation Technology

Directional solidification refers to the use of forced means in the solidification process, in the solidified metal and not solidified between the melt to establish a temperature gradient along a specific direction, so that the melt nucleation, along the direction opposite to the heat flow, according to the required crystallographic orientation for solidification. Directional solidification technology can better control the grain orientation of the solidified organisation, eliminating transverse grain boundaries, obtaining column crystal or single crystal organisation, and improving the longitudinal mechanical properties of the material.

Hot pressing and hot isostatic pressing

Hot pressing method and hot isostatic pressing method is powder pressing and sintering process at the same time, the basic principle of the two are the same, the main difference is the different ways of pressure. Hot pressing method is a one-way or two-way force, and hot isostatic pressing method is in all directions of the specimen are applied to the same pressure, so it can effectively eliminate the residual porosity of the product, to get close to the completely dense material, especially for some of the refractory intermetallic compounds should not be pressed and sintered.