Cobalt-free alloy material powder metallurgy valve seat and its preparation method and application

Abstract

The invention discloses a cobalt-free powder metallurgy valve seat material, the chemical composition and content thereof are: C: 0.8-1.2%, Cr: 4.0-6.0%, Mo: 5.0-7.0%, Ni: 0.8-1.8%, Cu : 12‑20%, Si: 0‑1%, lubricant: 0‑1%, and the balance is Fe. The invention also discloses a preparation method of a cobalt-free powder metallurgy valve seat material, which uses water atomized powder containing Cr alloy as the base powder, selects the formula amount of water atomized alloy powder containing Cr as the base powder, and then mixes Formulated amount of Mo-Fe alloy powder, Ni, C powder, Si and lubricant, through mixing, pressing, sintering and cold treatment, HRC is 40-50. The valve seat of the invention has the properties of wear resistance, corrosion resistance and high temperature resistance, is especially suitable for diesel engines, and the material price is only 1 / 2 of that of cobalt materials.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, in particular to a cobalt-free material powder metallurgy valve seat, a preparation method thereof and an application thereof to a diesel engine. Background technique [0002] At present, a large number of domestic automobiles use diesel engines as power, and diesel engines are the traditional power of tractors. As the key component of diesel engine, the valve seat is still widely used in cast iron materials. Due to the large casting pollution and the wear resistance of the valve seat is not ideal, most of the foreign valve seats are replaced by powder metallurgy materials. Aiming at the large domestic market, we started research and development in this field at the beginning of 2015. Since the operating temperature of diesel engines is about 100°C higher than that of gasoline engines, and the impact force of the valves is greater than that of gasoline engines, domestic diesel engine powder m...

AI Technical Summary

Problems solved by technology

Since the operating temperature of diesel engines is about 100°C higher than that of gasoline engines, and the impact force of the valves is greater than that of gasoline engines, domestic diesel engine powder metallurgy valve seats all contain cobalt, and the cobalt content ranges from 5 to 15%. Cobalt is a rare element and is expensive. , research on cobalt-free materials was carried out abroad in the 1990s, but there were few domestic reports. Due to the high price of cobalt-containing materials, the promotion of powder metallurgy valve seats in diesel engines was also restricted.

In 2010, we developed "a high-wear-resistant and low-cobalt powder metallurgy valve seat" and matched nearly a million gasoline engines with OEMs. So far, no quality problems of early wear have been found, but it is far-fetched to apply it to diesel engines. It is difficult to adapt to the high-temperature and high-impact working conditions of diesel engines. What material to choose can meet the requirements of powder metallurgy valve seats of diesel engines for wear resistance, corrosion resistance, and high temperature resistance? This is the problem to be solved by this invention.

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