1. Importance of pretreatment
Pretreatment of the stainless steel surface is the first step to ensure uniform deposition of the titanium layer. First, a thorough cleaning should be carried out to remove impurities such as oil, dirt and oxide layer on the surface. Oil will interfere with the bonding of titanium atoms to the stainless steel surface. The combination of organic solvent degreasing and alkaline solution cleaning can effectively remove oil. For the oxide layer, it can be removed by pickling or mechanical grinding. For example, pickling with a hydrochloric acid solution of appropriate concentration can dissolve the oxide layer on the stainless steel surface and expose a fresh metal surface.
Next is surface activation treatment, which can put the stainless steel surface in a state that is more conducive to the attachment of titanium atoms. The microstructure and energy state of the stainless steel surface are adjusted by electrochemical activation or plasma activation. For example, in the electrochemical activation process, stainless steel is used as an electrode. Under specific electrolyte and appropriate current and voltage conditions, the activity of surface atoms will be enhanced, creating good conditions for the uniform deposition of the titanium layer.
2. Accurate control of titanium plating process parameters
In the titanium plating process, accurate control of process parameters is the key. Temperature has a significant impact on the deposition uniformity of the titanium layer. Different titanium plating processes have their own suitable temperature ranges. For example, in vacuum titanium plating, the temperature generally needs to be controlled within a specific range. If the temperature is too low, the activity of titanium atoms is insufficient, the movement speed is slow, and it is difficult to diffuse evenly to the stainless steel surface; if the temperature is too high, the evaporation or sputtering rate of titanium atoms may be too fast, resulting in uneven local deposition.
Vacuum degree is also an important parameter. Appropriate vacuum degree can reduce the interference of gas molecules on titanium atoms, allowing titanium atoms to maintain a straight line trajectory in the process of flying to the stainless steel surface. For example, in physical vapor deposition (PVD) titanium plating, maintaining the vacuum degree at a stable high level can prevent titanium atoms from colliding with other gas molecules and changing the direction of movement, thereby ensuring that the titanium layer is evenly deposited on the stainless steel surface.
In addition, the deposition rate also needs to be reasonably controlled. Too fast a deposition rate will cause titanium atoms to accumulate before they have time to be evenly distributed on the stainless steel surface, resulting in uneven thickness of the titanium layer; while too slow a deposition rate will affect production efficiency. By precisely adjusting the power and other parameters of the Titanium plating equipment, the deposition rate can be precisely controlled.
3. Optimization of equipment and devices
The optimization of Titanium plating equipment and its related devices is of great help to the uniform deposition of the titanium layer. For magnetron sputtering Titanium plating equipment, the optimization of the target material is very critical. The use of high-quality and uniform titanium targets can ensure the uniform sputtering of titanium atoms. Moreover, the shape and structure of the target material will also affect the uniformity of sputtering. For example, compared with the flat target material, the rotating target material can achieve uniform sputtering of titanium atoms over a larger area, which helps to form a uniform titanium layer on the stainless steel surface.
The design of the workpiece fixture should also not be ignored. Reasonable fixture design should ensure that the distance between each part of the stainless steel workpiece and the titanium atom source is equal and the relative position is fixed during the Titanium plating process. For workpieces with complex shapes, the fixture should be able to be adjusted according to the shape of the workpiece to avoid certain parts being blocked and unable to be uniformly Titanium plating. For example, a fixture that can be adjusted at multiple angles is used to enable the workpiece to receive the deposition of titanium atoms in all directions during the Titanium plating process.
4. Process monitoring and adjustment measures
In the process of Titanium plating, the use of process monitoring means is an important guarantee to ensure the uniform deposition of the titanium layer. Optical monitoring equipment, such as optical film thickness monitors, can be used to monitor the deposition thickness and uniformity of the titanium layer in real time. Once it is found that the deposition thickness of the titanium layer in a certain part is different from that in other parts, the process parameters can be adjusted in time.
It is also necessary to regularly test the stainless steel samples after Titanium plating. The microstructure and uniformity of the titanium layer are analyzed by means of scanning electron microscopy (SEM) and other detection methods. If the test results show that the titanium layer is uneven, the Titanium plating process needs to be adjusted according to the test results, such as adjusting parameters such as temperature, vacuum or deposition rate, to ensure that the titanium layer can be uniformly deposited on the stainless steel surface during the subsequent Titanium plating process.
