Application of ultrafine iron powder in diamond tools
With the rapid development of economy in recent years, the application field of diamond tools has been gradually derived from the traditional stone processing to engineering construction and other professional fields. This transformation has put forward higher requirements on the quality, efficiency and cost of diamond tools. The properties of diamond tools are not only related to diamond concentration or quality, but also to the alloy bond that wraps the diamond.
As we all know, cobalt are widely used because of their excellent comprehensive performance, like good control force for diamond, excellent thermal hardness. However, the high cost of cobalt powder has put pressure on industry production.
In order to solve the problem of making diamond with higher cost, improving cutting efficiency and cutting life, and helping customers reduce costs, we gradually focus on iron, which has the same outer electronic structure as cobalt. Because of the same outer electronic structure, iron has very similar physical and chemical properties to cobalt, making itself an ideal substitute for cobalt.
- Due to the high melting point(1535℃)of ordinary iron powder, the temperature of diamond sintering process is strictly required, resulting in a narrow range of controllable process.
- Iron powder is very easy to erode diamond powder under high temperature environment, forming a loose graphite layer on the surface of diamond particles, greatly reducing the binding force of the bond to diamond, leading to a significant reduction in the cutting rate and cutting life of diamond.
- In high temperature environment, the other metal powder with low melting point in the bond is easy to be lost, and the iron-based bond produced finally has high deform-ability and wear resistance, which is not easy to peak and lacks sharpness.
- Carbonyl iron powder has a good spherical morphology, centralized particle size, but it results the diamond particles are mainly by point contact, the control force of diamond is low.
- Its uniform particles and good flow performance. Its coordination with other alloy powder is not high, and eventually lead to the low molding rate of diamond tools.
- The cost of carbonyl iron powder is slightly higher, the performance of imported products is far better than domestic, make the cost more higher.
Ultrafine iron powder(UIF), which has recently become very popular, provides the answer:
- Ultrafine iron powder has high purity, fine particle size, uniform particle size distribution, surface area and sintering activity are similar to cobalt.
- The sintering temperature of ultrafine iron powder is much lower than that of conventional iron powder, and it can be sintered well at 700-900℃, and the cross section of sintered products is fine and uniform.
- Ultrafine iron powder is used to wrap diamond particles in surface contact, which has good ability of encasing diamond and high control force.
- The fluidity of ultrafine iron powder is slightly worse than carbonyl iron powder, and it begins to enter the liquid phase at 690℃.Therefore, it has a high degree of alloying with other powders of the bond, and has good form-ability. Especially, it has a significant effect on improving the forming of the bond with a large number of alloy powder.
- The finer the particle size of iron powder is, the higher the bending strength and hardness of the finished product will be, but the increase will be reduced after reaching the peak at 850-900℃.
- The cost of ultrafine iron powder is much lower than cobalt powder oreven carbonyl iron powder.
- Because ultrafine iron powder has low sintering temperature, can effectively reduce energy consumption, has good energy saving.
In general, in diamond grinding block and grinding wheel products, ultrafine iron powder can improve the density, hardness and bending strength of sintered body so as to improve the service life; In the diamond head products, the excellent support and control force of ultrafine iron powder on diamond particles make the tools sharper and more durable.