CVD Diamond Tool Brazing

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With the development trend of lightweight and high-strength workpiece materials, more stringent requirements are put forward for the tools used in material cutting. Diamond tools have the advantages of extremely high hardness and wear resistance, low friction coefficient, high elastic modulus, high thermal conductivity, low thermal expansion coefficient, and low affinity with non-ferrous metals. It can be used for precision machining of non-metallic hard and brittle materials such as graphite, high wear-resistant materials, composite materials, high-silicon aluminum alloys and other tough non-ferrous metal materials. There are many types of diamond tools with significant performance differences. The structures, preparation methods and application fields of different types of diamond tools are quite different. At present, commonly used diamond tools include CVD diamond film coating tools and polycrystalline diamond (PCD) tools.

Chemical vapor deposition (CVD) diamond has better impact resistance than single crystal diamond. Compared with polycrystalline diamond (PCD), it can greatly improve tool life and ensure machining accuracy. However, the thicker the diamond film of the CVD-coated tool, the worse the bonding strength between the film and the substrate, and the general film thickness is limited to less than 50 microns. Therefore, the diamond thick film is peeled off from the original substrate, cut into the shape and size required by the tool, and then welded to the tool substrate material. The obtained diamond thick film welded tool has both single crystal diamond tools and diamond film coated tools. With the advantages of longer life and more stable cutting performance, it is a new type of cutting tool with extremely wide applications.

The main welding method currently used is vacuum brazing. Vacuum brazing technology has incomparable advantages and has been rapidly developed and widely used in industrially developed countries in the world.

Advantages of Vacuum Brazing
1. Vacuum brazing is carried out in a vacuum atmosphere, which significantly improves the corrosion resistance of the product, avoids various pollution, pollution-free processing equipment costs, and has good safety production conditions.

2. Vacuum brazing can save a large amount of expensive metal flux, and does not require complicated flux cleaning procedures, which reduces production costs.

3. Vacuum brazing solder has good wettability and fluidity, and can weld more complex and narrow-channel devices. Vacuum brazing improves the yield of products and obtains a strong and clean working surface.

4. Compared with other methods, the internal structure and fixtures of the furnace have a long service life, which can reduce the maintenance cost of the furnace.

5. There are many materials suitable for vacuum brazing, such as: aluminum, aluminum alloy, copper, copper alloy, stainless steel, alloy steel, low carbon steel, titanium, nickel, Inconel, etc. can be brazed in a vacuum electric furnace For welding, the designer determines the required material according to the use of the brazing device, among which aluminum and aluminum alloys are the most widely used.

Process flow:

The thickness of CVD diamond film is 110Pm; the brazing substrate material is cemented carbide YG8, and the solder composition is 90 (Ag72-Cu)-10Ti. The workpieces are brazed in the RHVB vacuum brazing furnace. The vacuum degree is 5×10-3Pa, and the heating temperature is 880°C to 940°C. Holding time t=20min; cooling with the furnace. Vacuum brazed diamond tools have high bonding strength, good quality and long service life, and are high-quality products among diamond tools.

Equipment selection: A process technology must be matched with excellent equipment to play a role, and the brazing furnace selected in vacuum brazing is very important. The RHVB vacuum high-temperature brazing furnace produced by SIMUWU is an excellent product for handling such processes. With its excellent temperature control accuracy and temperature uniformity, it can realize the brazing of workpieces evenly, so as to achieve high-level brazing standards, reduce scrap rate, increase production efficiency and reduce costs.