Presentation of brazing technology in diamond tools

Diamond carcass (commonly known as tool head) sintering process is also a diffusion brazing process. Diamond tool brazing is divided into three categories: single diamond tool brazing, diamond tool brazing and PDC composite brazing.

 

Hot pressing or cold pressing sintering of diamond head is a typical diffusion brazing process. In the early stage of making diamond head, it is generally used to melt and diffusion brazing high temperature metal powder with low temperature metal powder to further inlay and control diamond. With the development of technology, active prealloy powder containing carbide forming elements (chromium, titanium, vanadium, molybdenum, etc.) appears.

 

The reactive prealloy powder reacts with diamond to form carbide to achieve diffusion brazing or brazing connection. The formation of carbide is slow, which is a process of mutual diffusion and migration between active elements in prealloy powder and carbon elements in diamond. In order to achieve atomic diffusion and reaction, hot pressing sintering process is easier to achieve this kind of diffusion.

In the brazing of single layer diamond tools, active brazing filler metal or nickel-based brazing filler metal is generally used. By forming elements or alloys with strong carbide, the chemical metallurgical combination between the matrix material and diamond is realized, and the holding power of the brazing filler metal layer on diamond is improved. Single-layer brazing tool has a large proportion of diamond exposure and is not easy to fall off, so single-layer brazing diamond tool has sharp cutting and good chip removal.

 

The orderly arrangement of diamond not only realizes the reasonable arrangement of diamond layer on the tool surface, gives full play to the cutting function of diamond, but also greatly reduces the amount of diamond, reduces the tool cost and improves the cutting efficiency.

 

The brazing of diamond tool head has its uniqueness. Firstly, the tool head is powder metallurgy products, and there are countless pores in the tool head. Secondly, the tool head is sintered products, there are oxides on the surface and inside the tool head; Again, the components of the tool head are not the same, and the requirements for brazing materials and brazing processes vary.

 

Due to the limited heating temperature allowed by PCD (generally no higher than 720 ~ 780℃), the brazing material mainly uses silver base filler metal, but the general silver base filler metal has low heat resistance temperature and poor wettability to diamond and carbide. At present, there are special PDC tool brazing materials, which can meet the requirements of PDC brazing by improving the high temperature strength and fatigue properties of brazing filler metal and adjusting the reasonable brazing process.