Refractory metal tantalum with high melting point (2996 ℃, second only to W, Re), high temperature and high strength, low thermal expansion coefficient, electrical conductivity, good welding performance, high corrosion resistance can be comparable to platinum (room temperature), etc, are widely used in electrical, chemical, aerospace, medical, military and other fields, is the indispensable material in high-tech fields. However, tantalum has very few reserves in the earth, only 0.0002% of the earth's crust quality. Therefore, the use of tantalum resources is of great significance. Chemical vapor deposition (CVD) is a chemical gas instead should generate solid sediments in the heated solid surface process, with deposits of high purity, density, sedimentary speed, can be multielement alloy deposition, etc. Because of CVD technology unique advantages, at present this technology has been widely applied in preparation of inorganic coating material surface modification, material purification, development of new crystal and various single crystal deposition, glassy state of inorganic membrane materials. A layer of tantalum coating is deposited on the inner wall of the workpiece or container by chemical vapor deposition, which can greatly reduce the use of materials while ensuring the good corrosion resistance of the materials. Hot wall type resistance furnace heating, commonly used chemical vapor deposition reactor wall temperature and deposition substrate temperature, so the reactor wall also deposition reaction, waste of raw materials and cause the pollution of the reactor. Cold wall chemical vapor deposition using induction heating mode, the only substrate is heated, it can only happen on matrix deposition reaction, greatly reduces the waste of raw materials, to solve the pollution problem of the reactor, to enhance the generality of the reaction mechanism. In the study of chemical vapor deposition of tantalum, tantalum sediments organization performance under different process conditions change rule, in order to gain good performance of tantalum sediments, has very important practical significance and theoretical value.
The organization and performance of the coating strongly depends on the nucleation and growth condition, its temperature were the main influencing factors, the shape, the reaction gas flow pressure, reaction chamber and proportion, the deposition temperature is the most important parameters affecting the effects of deposition. This experiment mainly analyzes the composition, structure and surface effect of sedimentary temperature on the sedimentary layer, and provides some references for the application of chemical vapor deposition of tantalum.
The structure of the sedimentary layer is the structure of the body centred cubic structure, the composition of the sedimentary layer and the crystal structure and the obvious influence of the deposition temperature, and the change of the deposition temperature has certain influence on the selection and growth of the sedimentary layer. The microstructure of tantalum deposits gradually disappeared with the increase of deposition temperature, and the size of columnar grains gradually increased. The surface particles of tantalum sediments are pyramidal and increase with the increase of sedimentation temperature.
