Types of brazing filler materials used for brazing diamond tools

Brazing diamond technology refers to a technique that uses a filler material capable of chemically reacting with diamond abrasive particles and forming a metallurgical bond with the steel substrate. There are various types of diamond brazing processes, which can be classified into laser brazing, induction brazing, and high-temperature brazing, depending on the heating method.

 

 

The principle of brazing diamond tools is to utilize elements with high affinity for carbon (such as Ti, Cr, and Zr) to undergo a chemical reaction during brazing, forming carbides and thus achieving a metallurgical bond between the diamond, filler metal, and substrate. For brazing diamond tools, the choice of filler metal directly determines the performance of the brazed diamond tool.

 

 

Common metal brazing materials are difficult to wet and spread on the diamond surface. While molten nickel exhibits a relatively small wetting angle on the diamond surface at high temperatures, copper does not wet the diamond surface at high temperatures. However, the addition of titanium to copper significantly improves the wettability of copper-based alloys on the diamond surface.

 

Currently, brazing materials used for diamond tools can be broadly classified into:

high-melting-point alloy brazing materials mainly based on nickel (e.g., Ni-Cr) and low-melting-point alloy brazing materials mainly based on silver and copper (e.g., Cu-Sn-Ti, Ag-Cu-Ti, and Ag-Cu-Cr).

 

 

 

Compared to nickel-based and copper-based brazing alloys, silver-based brazing alloys have lower melting temperatures and good wetting and spreading properties. Silver-copper-titanium alloys have low liquidus temperatures, which is more favorable for the production of diamond tools. Adding a small amount of titanium particles to metallic silver can enhance the brazing effect; the active element titanium reacts with the carbon in the diamond to form titanium carbide (TiC). However, due to the high price of silver and the high vacuum requirements for titanium, the brazing cost is high; at the same time, this brazing alloy has a relatively weak holding force on the diamond, making it prone to detachment during operation. Therefore, its application in diamond tool brazing is not very widespread. Silver-based brazing alloys are often used in special situations requiring low wear resistance.

 

 

Copper is a metal used in cables and has good corrosion resistance. Metallic copper has been widely used in the power and chemical industries, but its high cost has, to some extent, limited its scale. Copper-based brazing alloys are mainly divided into copper-tin-titanium and copper-tin-zirconium-titanium. According to the Cu-C metal alloy phase diagram, the solubility of element C in Cu is almost zero. Therefore, metallic copper is generally mixed with other metals to make mixed brazing alloys to improve the strength of the brazed joint. Due to the relatively high melting temperature of copper, the required brazing temperature is high, which can cause graphitization of the diamond. Adding tin can reduce the reaction temperature and save costs. In areas with good working environments and low wear resistance requirements, copper-based or silver-based brazing alloys can be selected to reduce the degree of diamond graphitization.

 

 

Nickel-based brazing alloys have high hardness, good corrosion resistance, good wear resistance, and good high-temperature performance, and have been widely used in the aerospace field. Since their inception, nickel-based brazing alloys have undergone extensive basic and applied research, and their commercial development has also received considerable attention. Ni-Cr alloys are commonly used brazing alloys for diamond tools. Using nickel-based brazing alloys for brazing diamond tools, the two complement each other's advantages, and the tools can be used in high-strength cutting, grinding, and drilling applications.

 

 

 

Due to the increasing difficulty in material processing, the original silver-based, copper-based, and nickel-based brazing alloys used in the manufacture of diamond tools can no longer meet the higher processing requirements, such as increasing the strength of the tool while maintaining its strength under existing brazing conditions, or reducing the internal stress of the tool. Many scholars have proposed the concept of composite brazing alloys, further improving the performance of brazed tools by adding hard or soft particles to the brazing alloy: adding nano- and micron-sized Al2O3 ceramic particles to Ag-Cu-Ti brazing alloy enhances the strength of the brazed joint and helps improve the wear resistance of the tool; adding μ-TiC particles to Ag-Cu-Ti composite brazing alloy improves the wear resistance of the brazing alloy and diamond, and prevents the formation of cracks in the diamond grinding wheel during brazing; adding different amounts of Hf to enhance Ni-Cr-Si-Cu-Sn boron-free brazing alloy achieves the purpose of lowering the melting point of the brazing alloy and refining the grain structure.

 

Advantages and disadvantages of several different brazing materials

 

Huice Company supplies various brazing diamond tools with sharp grinding, affordable prices, and direct sales from manufacturers. Welcome to inquire.

Contact now

 

 

Reference:

• "Analysis of Solder Materials for Diamond Grinding Particle Brazing" Hou Miao
• "Development of Brazing and Diffusion Welding in Diamond Tool Manufacturing" Li Shengnan