4. Functional coating: Plasma spray supersonic spray superconducting ceramic coating has been successfully applied. Superconducting ceramic coating in the magnetic shielding, microwave components, various types of transmitters, quantum electronic devices, etc. show a good application prospects. In the 0.1mm iron coated with 30μm BaTiO3 coating, the dielectric constant of more than 6000, has been widely used in ceramic chip capacitors. The Al2O3 coating formed by plasma spraying can withstand voltage of 2500 ℃ or higher at high temperature of 1300 ℃ when the thickness is less than 1mm, which meets the requirement of high temperature electrical insulation. Titanium alloy matrix coated with 50-75μm hydroxyapatite and other bioactive ceramics, providing a good chemical compatibility, therefore, can be used as an ideal artificial bone material to be used.