Passivation is the process of converting the surface of a metal into a state that is less prone to oxidation (forming an oxide film), in order to delay corrosion. Titanium alloys inherently have extremely strong passivation properties, and their surfaces can quickly form a dense natural oxide film, enabling them to have excellent corrosion resistance in various harsh environments.
Common passivation processes
Electrochemical passivation:
Principle: Utilizing electrochemistry to form a dense oxide film on the titanium alloy surface and to prevent corrosion and scratches.
Characteristics: The oxide film is extremely thin. By controlling its thickness (0.01μm - 0.15μm), it can cause rich color refraction, and is widely used in consumer products such as titanium cups and titanium chopsticks.
Heat treatment passivation:
Principle: By heating and then cooling fast, a dense oxide layer is formed on the titanium alloy surface.
Function: Significantly enhances corrosion resistance of titanium alloy, suitable for chemical equipment where long-term stable operation is required in harsh environments.
Titanium alloy acid pickling and passivation process
Pre-treatment: It is necessary to first remove surface contaminants using mechanical methods, followed by oil removal and degreasing. This is the foundation for ensuring the uniformity and density of the subsequent oxide film.
Process control: The acid pickling process usually uses nitric acid solution (Common ratios are HNO₃: water = 1:10 or 1:15). It is crucial to strictly control the ratio and the operation to avoid the generation of harmful "yellow smoke", which can pollute the environment and cause health problems.
Pickling time: a time range of 5 to 10 minutes is considered to be the most suitable in pickling process. If the time is too short, the reaction will not be sufficient. If the time is too long, due to the strong hydrogen affinity of titanium, it is prone to cause "hydrogen embrittlement" (reduced toughness), which will seriously affect the material's performance.
Post-treatment: After pickling, thorough water washing must be carried out to remove any remaining acidic substances; subsequently, drying treatment should be conducted to prevent the residue of moisture from causing secondary corrosion or rusting.
Baoji Yibaite New Materials Technology Co., Ltd is the best manufacturer and supplier for the titanium products with the best price.
Welcome to our company and hope to be your best partner.