is made of diamond and metal powder sintering, in many metal powders, iron powder is the most common and very used, then the question arises: why use iron powder in diamond segment? How much does it cost?
Let's first solve the first question, why use iron powder in diamond segments? There are several main reasons. 1: Iron powder and diamond have a good wetting (wetting refers to the existence of two insoluble liquids and solids, liquid first wet solid surface ability, that is, a liquid in a solid surface spread ability or tendency), what does it mean? When iron powder and diamond sinter at high temperatures, the energy of the surface layer molecule is higher than that of the inner molecule because the molecular state of the diamond surface layer is different from that of its internal molecules. When solid diamond comes into contact with iron powder that becomes a liquid, once the interface is formed, the adsorption phenomenon of reducing surface energy occurs, and the iron powder of the liquid is spread out on the surface of the solid material. The liquid spread on a solid surface is called wetting, the ability of the liquid to spread on a solid surface is called liquid-to-solid wetting, while iron on the diamond surface spread wetting contact angle of 50%, is better than the higher material price of cobalt and nickel. Wetting determines the fixed strength of diamond, the higher the wetting, its chemical holding force and physical holding force is also higher.
2: During sintering, the adhesion between iron and diamond is very strong. Adhesion (adhesion is the mutual attraction between the contact parts of two different substances.) This attraction is a manifestation of the attraction of interaction between the molecules of two substances, which can only be shown if the distance between the two molecules is very small (less than 10-8 meters). Because from a microcosmic point of view, the surface of a solid is often uneven, so the two solids cannot show the role of adhesion when in contact. Because liquids and solids can come into close contact, adhesion can be shown between liquids and solids. In the process of diamond segment sintering, the adhesion of iron to diamond is 3.4 x 10-7J/cm2, which is better than cobalt and nickel.
3: Fe powder in the sintering process, high temperature, can produce carburizing body Fe3C and carbonated ferrous Fe2C, these two structures of powder has a higher melting point, can also be with boron, W, Mo involved in the production of more kinds of carbide. These carbides have higher melting points, allowing the segment to deform quickly during the cutting process due to high heat.
4: Fe has a lower coefficient of line expansion (line expansion coefficient is the ratio of the length of a solid substance to its length at the original temperature (not necessarily 0 degrees C) for each change in the temperature of a solid substance, called a "linear expansion coefficient". The coefficient of line expansion is close to diamond, which also allows the diamond segment to not cool down and crack during the cutting process.
5: During sintering, iron will have some slight etching reaction to diamond, but this etching will not reduce the strength of diamond, but will improve the tire body's ability to hold diamond. Because the etched part of the diamond is not in the form of graphite, but spread to the diamond surface of the iron-containing metal film, according to a certain law of distribution, such a close distribution, will make diamond and iron binding very close.
Now that you know why, how much iron powder is most appropriate?
When it comes to how much iron powder to put in, this needs to be related to the cutting object of the diamond segment to be manufactured and the design direction, for example, if used for cutting relatively hard, wear resistance is very high granite, iron powder will choose the ratio of 50-60 percent, if the cutting is softer, less wear resistance marble stone, iron powder will choose less than 10% of the content of iron powder, to prevent the tire body is too wear-resistant, resulting in difficult conditions. In general, the content of iron powder is not certain and needs to be deployed according to the actual situation.