As important biomedical materials, titanium materials and their alloys have shown significant advantages in oral restoration, but their special physical and chemical properties place stringent requirements on processing technology. This article systematically sorts out the key points and application characteristics of three mainstream surface treatment technologies given the processing difficulties of titanium materials.
1. Mechanical grinding: breakthrough application of superhard abrasives
Given the processing difficulties caused by the high reactivity of titanium materials (rapid reaction with oxygen and nitrogen at room temperature), low thermal conductivity (16.4 W/m·K), and strong adhesion characteristics, traditional abrasives are prone to surface burns (>300℃ phase transition temperature) and microcrack propagation. Studies have shown that the use of superhard abrasives such as diamond (HV10000) or cubic boron nitride (HV4500), combined with the optimal linear speed of 900-1800m/min, can increase the grinding ratio by 3-5 times, and the surface roughness Ra value can be stably controlled within 0.2μm. Special attention should be paid to maintaining the self-sharpening property of the grinding tool to avoid local temperature rise caused by abrasive grain passivation.
2. Ultrasonic assisted grinding: precision machining solution for complex structures
The instantaneous cavitation effect is produced by 20-40kHz high-frequency vibration so that 100-800# silicon carbide abrasive grains can achieve multi-dimensional motion trajectory. Clinical tests show that this technology improves the processing efficiency of the implant thread root (R＜0.2mm) by 60%, and the surface residual stress is reduced to ＜200MPa. However, due to the amplitude attenuation law (amplitude loss rate ≈1/d²), when processing castings with a volume of ＞15cm³, a multi-axis linkage device is required to compensate for energy loss.
3. Electrolytic mechanical composite grinding: an innovative path for mirror processing
Based on the electrochemical-mechanical synergistic mechanism, a conductive diamond grinding wheel (φ6mm, concentration 75%) can be used to achieve a balance between a material removal rate of 0.8mm³/min and a surface roughness of Ra0.05μm under the conditions of 0.9% NaCl electrolyte, 5V DC electric field and 3000rpm rotation speed. Anodic dissolution (accounting for about 35% of material removal) effectively suppresses mechanical stress concentration and is particularly suitable for thin-walled components (thickness <0.5mm) processing. At present, the problem of uniform processing of multiple curved surfaces of denture brackets is being overcome through pulse power supply (duty cycle 30%-70%) and three-dimensional electric field control technology.
The current technological development shows a trend of multi-energy field composites, such as laser-assisted ultrasonic electrolytic composite polishing and other new technologies that can improve surface integrity to the nanometer level. In the future, it is necessary to focus on breaking through the contradiction between processing efficiency and adaptability to complex morphology and promoting the development of titanium material processing towards intelligence and precision.
