Research status of domestic and foreign research on wear-resistant materials of slurry pump over-flow parts.

At present, the research on the wear resistance of slurry pump flow parts at home and abroad mainly includes the following two aspects: the improvement of the composition of high chromium cast iron and the utilization of new materials and new processes.

First, high chromium cast iron modification

1. Using ultra-high chromium alloy material to improve wear resistance

The ultra-high chromium alloy material (Cr24-30%) is used to obtain the number of carbides and hard phases mainly composed of M7C3 type. When the ratio of Cr/C is 7-8, the material can withstand large impact loads.

The key process is to use a suitable heat treatment process to eliminate the structural segregation, coarse grain and large casting stress that may be caused by ultra-high chromium, and obtain the ideal martensite + carbide + austenite structure.

According to the literature, ultra-high chromium alloy materials have been used in dredging pump impellers for large dredgers, in which the C content is 2.4%-3.0% and the Cr content is 24%-29%.

2. Phase diagram calculation to determine the applicable working conditions of different C/Cr ratio high chromium cast iron

The relationship between the equilibrium phase mass fraction and the carbon content of high chromium cast iron was calculated by software, and the selection principle of the flow parts under different working conditions was summarized. The Cη5 type high chromium cast iron belongs to the sharp-angled and neutral slurry medium. The preferred material for working overcurrent parts;

High carbon Cr27 and low carbon Cr27 high chromium cast irons are suitable for use in secondary wear and erosion conditions;

Low carbon Cr38 is suitable for highly corrosive slurry media; high carbon Cr38 is suitable for working environment where corrosion and wear are combined.

3. Modification of carbides by modification treatment

Modification can change the morphology and distribution of eutectic carbides in high-chromium cast iron, which makes the development of brittle carbides to isolation and spheroidization, reduces the splitting effect of carbides on the matrix, and fully exerts the ability of the matrix to absorb cracks and improve the material. toughness.

Instant metamorphism in the metamorphic treatment process is an ideal process, which can effectively suppress the occurrence of decay, refine the carbides significantly, further improve the carbide type, and make the carbides more dispersed in the matrix.

4. Effect of trace elements on the wear resistance of high chromium cast iron

The addition of niobium to high chromium cast iron improves the wear resistance of high chromium cast iron. After the high-chromium white cast iron through-flow parts of manganese molybdenum are used to reduce the amount of retained austenite in the finished product by destabilization treatment, when Cr/C is 6.5, the product has excellent toughness.

Second, the use of new materials and new processes

1. Ceramic material application

Abroad, South Africa's Wiltkeke supplied a slurry pump impeller made of alumina ceramics to the Zuoweiwei mine in Zimbabwe, installed on the cyclone feed pump of the mine.

Originally this pump was a hard nickel alloy impeller, which had an average service life of only 3-4 weeks.

Due to the fast wear rate of the hard nickel alloy impeller, the working efficiency of the slurry pump drops rapidly within 2-4 weeks after installation, while the new alumina impeller shows signs of wear after 6 weeks of operation under normal conditions. After 9 weeks of wear, the main The wear site is the suction edge of the blade and the ribs of the feed plate.

The impeller's steel frame is fitted with an elastomeric material to increase structural strength. This impeller has been widely used in southern Africa and other parts of the world, and its service life is reported to be lower than conventional low carbon steel, rubber and hard nickel alloys. The material is longer.

2, paste and weld wear-resistant materials

The use of high-strength, high-temperature adhesives or special welding processes to composite wear-resistant engineering ceramics on the surface of the blade is another important new process.

The use of adhesive and inlay technology to form a surface layer with excellent wear resistance on the working surface of the pump impeller can greatly improve the wear life of the impeller.

In addition, the anti-wear treatment of brushed ceramic emery material and the surfacing process using high-alloy welding rods to repair the damaged slurry pump over-current components show that the repair has considerable economic benefits.

Third, the conclusion

Throughout the above development status, it can be known that the development of wear-resistant materials for slurry pump over-flow parts presents a diversified trend, and researchers have explored new materials and new processes for different working conditions. The improvement of the wear resistance of the slurry pump overcurrent parts can reduce the consumption of materials, reduce maintenance costs and energy consumption, thereby improving production efficiency and economic benefits. Accelerate the research and development of wear-resistant materials for over-flow parts of slurry pumps in China, and develop new wear-resistant slurry pumps for different working conditions with important social and economic benefits.