The roles of various elements in the binder of diamond saw blades

Diamond saw blades are made by welding diamond segments to a base(steel body). The diamond segments are made from fine diamond abrasive particles and metal powder under high temperature and high pressure. One of the factors affecting the performance of diamond segments & saw blades is the metal elements in the binder of the diamond segments.

This article, based on over twenty years of experience in manufacturing diamond tools, briefly analyzes the role of different elements in the binder of diamond saw blade segments.

 

 

Copper and copper-based alloys are the most widely used metals in the metal binders of diamond tools, with electrolytic copper powder being the most common. Copper and copper-based alloys have low sintering temperatures, good formability and sinterability, and good mutual solubility with other elements. Although copper hardly wets diamond, alloys of copper with certain elements can significantly improve its wettability to diamond. For example, copper alloys made with one of the carbide-forming elements such as Cr, Ti, W, V, and Fe can greatly reduce the wetting angle of the copper alloy to diamond. Copper can form various solid solutions with nickel, cobalt, manganese, tin, and zinc, strengthening the matrix metal.

 

 

 

Tin is an element that reduces the surface tension of liquid alloys and has the effect of reducing the wetting angle of liquid alloys to diamond. It is an element that improves the wetting of the binder metal to diamond, can lower the melting point of the alloy, and improve press formability. Therefore, Sn is widely used in binders, but its use is somewhat limited due to its large coefficient of thermal expansion.

 

 

In diamond tools, Zn and Sn have many similarities, such as low melting point and good deformability. However, Zn is not as effective as Sn in changing the wettability to diamond. Metallic Zn has a high vapor pressure and is easily vaporized, so the amount of Zn used should be carefully controlled.

 

 

 

Aluminum is an excellent light metal and a good deoxidizer. At 800°C, the wetting angle of Al to diamond is 75°, and at 1000°C, the wetting angle is 10°. Adding aluminum powder to the binder of diamond tools can form carbides Ti3AlC and intermetallic compounds TiAl in the matrix alloy.

 

 

Iron has a dual role in binders: firstly, it forms cementite carbides with diamond; secondly, it alloys with other elements to strengthen the matrix. Iron has better wettability to diamond than copper and aluminum, and its adhesion to diamond is higher than that of cobalt. Moreover, dissolving an appropriate amount of carbon in the Fe-based alloy is beneficial for its bonding with diamond. That is, moderate etching of the diamond by the Fe-based alloy can increase the bonding force between the binder and the diamond. In actual production, the fracture surface of the saw blade generally does not show smooth, exposed diamond, but rather a layer of alloy covering it, which is a manifestation of the strengthened bonding force.

 

 

Co and Fe are both transition elements with similar characteristics. Under specific conditions, Co can form the carbide Co2C with diamond and cover the diamond surface with an extremely thin cobalt film. Thus, Co can reduce the interfacial tension with diamond and has a strong adhesion to diamond in the liquid phase, making Co an excellent bonding material.

 

 

Nickel has a face-centered cubic structure, good ductility, toughness, and oxidation resistance. It is infinitely miscible with copper. Nickel is an element that promotes austenitization and can expand the α-phase region. It reacts with carbon with difficulty, and the interfacial reaction with diamond hardly occurs during high-temperature sintering. However, liquid Ni can firmly adhere to the surface of carbon fibers, forming an extremely thin film.

 

In diamond tool binders, Ni is an indispensable element. In Cu-based alloys, adding Ni allows for infinite miscibility with Cu, strengthening the matrix alloy, inhibiting the loss of low-melting-point metals, and increasing toughness and wear resistance. Adding Ni and Cu to Fe-based alloys can lower the sintering temperature, reduce the thermal erosion of the diamond by the bonding metal, and selecting appropriate proportions of Fe and Ni can greatly improve the holding force of the Fe-based binder on the diamond.

 

 

In metal binders, manganese has a similar effect to iron, but it has stronger penetration and deoxidation capabilities and is easily oxidized. Generally, the amount of Mn added is not high, and it has the functions of deoxidation and strengthening the matrix.

 

 

 

Chromium is a strong carbide-forming element. In the matrix of diamond grooved saw blades, chromium can play a sound-damping role, which is related to the activation energy of Cr. Adding a small amount of Cr to a Cu-based matrix can reduce the wetting angle of the copper-based alloy to diamond and improve the bonding strength between the copper-based alloy and diamond.

 

 

Titanium is a strongly carbide-forming element that is easily oxidized and difficult to reduce. In the presence of oxygen, Ti preferentially forms TiO rather than TiC. Metallic titanium is a good structural material, possessing characteristics such as minimal strength reduction at high temperatures, heat resistance, corrosion resistance, and a high melting point. Studies have shown that adding an appropriate amount of titanium to the diamond saw blade matrix is ​​beneficial for improving the service life of the saw blade.

 

 

Tungsten is a strong carbide-forming element and can be used as a framework material. Depositing a certain amount of tungsten powder on the diamond surface, after sintering, forms WC, W₃Co₃V, and W₄Co₂C on the diamond surface. Tungsten has good compatibility with other binder metals such as Cu, Co, Ni, and Fe.

 

 

 

 

Rare earth elements can effectively lower the melting point of the alloy; La and Ce have strong deoxidizing, desulfurizing, and deammoniating effects, inhibiting the segregation of oxides, sulfides, and nitrides at the interface; they can improve the bending strength of the material; in high-Co or pure Co matrices, the addition of the rare earth element Ce is beneficial to improving the mechanical properties of the matrix, and adding a small amount of Ce (approximately 0.12 wt%) to a bronze-based matrix can achieve good results.

 

 

 

Silicon has a linear expansion coefficient close to that of diamond, lower than other metals; it exhibits smaller volume effects during heating and cooling; silicon has good compatibility with diamond; silicon can lower the melting point of the alloy and has strong deoxidizing ability.

Quanzhou Huice Company has over twenty years of experience in the production, manufacturing, and research and development of diamond tools, specializing in the manufacture of various diamond tools.

Contact now