Micron diamond coating and nano diamond coating
According to grain size, CVD diamond coating can be divided into micron diamond coating and nano diamond coating.
Micron diamond coating grain size is usually between 500 nm and a few microns, micron diamond coating surface is rough (Ra value is usually a few hundred nanometers), coating toughness and crack propagation resistance is poorer, surface crack is easy to cause peeling coating, extended along the grain boundary area makes the tool surface before did not reach the standard of dulling coating have fall off.
Nano diamond coating is composed of nanoscale diamond grains distributed in clusters. The grain size is usually less than 100 nm, and the surface is smooth (Ra value is less than 100 nm). Compared with micron diamond, its bonding strength with matrix is relatively lower, and abnormal failures such as coating shedding are easy to occur in the process of processing.
Diamond coated tool selection:
The main basis is the property of workpiece material and processing quality requirements.
For EDM graphite mold processing, the essence of the milling process is similar to the "grinding" process, at this time, the number of "micro edge" on the tool surface is large and wear-resistant, so the micron diamond coating with larger grains should be selected.
For the mold used in ceramic processing, high surface finish is required, nano diamond coating should be used in the finishing stage.
In the processing of aluminum alloy, the phenomenon of "sticking tools" is more serious than tool wear, and the requirement of tool wear resistance is relatively low, so nano diamond coating with low friction coefficient should be selected.
For carbon fiber composite materials, micro/nano composite diamond coating should be used because of the strong abrasion performance of the fiber material itself, which requires the tool to have good wear resistance and reduce the cutting force and cutting heat in the processing process.
In particular, the choice of diamond coating thickness is not "the thicker the better", diamond coating quality is more than the role of thickness with the improvement of wear resistance.
---EDITOR: Anna Wang
---POST: Doris Hu