There are many surface treatment methods for titanium, including ion nitriding (or plasma nitriding), surface deposition of titanium nitride, ion implantation, surface alloying and surface spraying of ceramic coatings.
1. High temperature and wear-resistant coating preparation technology for titanium alloy components
1) Wear-resistant coating preparation technology
Wear is one of the main causes of mechanical parts failure, accounting for approximately 60% to 80% of mechanical parts failures, and has a great impact on the life and reliability of mechanical parts. The wear resistance of titanium and titanium alloys is relatively poor, the friction coefficient is large, and wear failure is prone to occur. Wear-resistant coating preparation technology is an important means to improve the wear resistance of titanium and its alloys. Currently, the more researched process methods include thermal spraying, electroplating and chemical plating, vapor deposition, ion implantation technology, nitriding, and 170 marine nitriding. Engineering titanium metal materials carbon, boronization, micro-arc oxidation and composite surface treatment technology, etc.
2) High temperature resistant coating preparation technology
With the application of titanium alloys in ship gas turbines, higher requirements have been placed on their high-temperature oxidation resistance. When titanium is used as gas turbine blades, etc., it has poor resistance to high-temperature oxidation and is prone to "oxygen embrittlement". That is, after long-term exposure to high-temperature air, a brittle oxide layer will form on the surface of titanium, which will embrittle the titanium alloy and reduce the elongation. It can reach up to 50%. However, it is difficult to simultaneously improve the oxidation resistance of titanium alloys through alloy composition optimization design or microstructure control methods. Surface modification and surface coating technologies must be used to improve it.
3) High temperature wear-resistant coating preparation technology
Ship gas turbine blades are subject to wear under high-temperature conditions. Due to the dual effects of wear and high temperature, the damage rate of components is accelerated. Therefore, it is very important to study the high-temperature wear mechanism, design high-temperature wear-resistant coatings, and improve high-temperature wear resistance. meaning. Ceramic materials are mostly combined with ionic bonds and covalent bonds. They have high chemical bond energy and strong inter-atomic bonding force, which makes ceramic materials have the advantages of high melting point, high hardness, high chemical stability and low friction coefficient. Through plasma spraying and laser cladding The technology can prepare ceramic coating on the surface of titanium alloy to form a ceramic titanium alloy composite. Current preparation methods include plasma spraying nano-ceramic coating, cold spraying nano-TiO2 coating, laser spraying and laser cladding.
2. Preparation technology for friction-reducing and wear-resistant coatings on titanium alloy components
1) Antifriction coating preparation technology
In response to the friction-reducing needs of components such as marine gears, pistons, valves, and titanium springs, self-lubricating materials such as graphite, molybdenum disulfide, polytetrafluoroethylene, lead oxide, and fluoride are added to form a gap between the two surfaces. A layer of solid lubricating film can reduce the friction coefficient and increase the wear resistance of the material. Antifriction coating preparation methods include magnetron sputtering MoS z coating, plasma spraying PTFE coating, electrodeposition process preparation (Ni-P)-graphite composite coating technology, etc.
(2) Preparation technology of anti-friction and wear-resistant coating
In response to the actual needs for friction reduction and wear resistance of titanium materials, through appropriate surface treatment technology of titanium and titanium alloys, antifriction and wear-resistant coatings are prepared on the surfaces of titanium and titanium alloys to improve the friction of two objects in relative motion, that is, the friction pair. Wear resistance and reducing friction loss during movement can achieve the purpose of lowering the friction coefficient, reducing friction and controlling wear. Preparation methods for anti-friction and wear-resistant coatings include plasma carbonitriding, sulfur nitriding, sulfur nitrocarburizing, magnetron sputtering Ti/MoS2 coating, physical vapor deposition TiAIN/TiN composite coating, physical vapor phase Deposition of TiN/TiCN multi-layer composite coatings, cathode arc source deposition of diamond-like carbon films, high-power high repetition rate pulse excimer laser preparation of diamond-like carbon films, etc.
3. Preparation technology of insulating coating for metal components
Although titanium alloys have excellent corrosion resistance, when titanium alloys are used in contact with dissimilar metals in seawater and marine atmospheric corrosive environments, a potential difference is generated due to the high potential of the TiO2 film electrode naturally formed on the surface, and the potential is lower. The surface of dissimilar metals will be oxidized, causing material corrosion failure. Therefore, in order to avoid corrosion in seawater of pipes, piping accessories and other shipbuilding parts made of copper, copper alloy and steel that are in contact with titanium alloy during use, appropriate surface treatment methods must be used to form a coating on the surface of the titanium alloy. An insulating anti-corrosion coating to improve the corrosion resistance of titanium and other metal materials. The preparation methods of insulating and anti-corrosion coatings include micro-arc oxidation ceramic insulating coating, micro-arc oxidation nano-ceramic coating, anodized insulating coating, etc.
