Gear pump industry has great potential for development.
Bushing bore, sleeve outer circle, gear pump shaft and shell uniform wear and scratches between 0.02-0.20mm, should adopt high hardness, strong combination with the body parts, good wear resistance of arc spraying Repair process. Arc spraying process: the working surface pretreatment → preheat → spray bonding the bottom → spraying the working layer → cooling → coating processing.
Spraying process, the requirements of the workpiece without oil, no rust, surface roughness, preheating temperature is appropriate, the bottom combined with a solid, smooth working layer, the material particles melt-bonded reliable, good wear resistance and corrosion resistance. Spray coating quality and workpieces surface treatment and spraying process has a great relationship, therefore, choose the appropriate surface treatment and spraying process is very important. In addition, the non-sprayed portions adjacent to the coated surface should be bundled with a thin sheet of metal or copper during spraying and spraying.
The basic bonding strength of the coating is related to the substrate cleanliness and roughness. Before spraying, the basic surface cleaning, degreasing and surface roughening and other pretreatment is an important process spraying process. The first part of the spray should be sprayed with gasoline, acetone degreasing treatment, with a file, fine sandpaper, whetstone will remove the fatigue layer and the oxide layer, exposing the metal color. Then roughening treatment, roughening treatment can provide surface compressive stress, increase the bonding area and clean the surface of the coating and the substrate, reduce the stress when cooling the coating, ease the internal stress of the coating, it is conducive to the increase of adhesion . Sandblasting is the most commonly used roughening process, sand to sharp, hard as well, the choice of quartz sand, emery and so on. Rough fresh surface easily oxidized or polluted by the environment, it should be timely spraying, if placed more than 4h will be re-roughened.
The temperature difference between the coating and the substrate surface causes shrinkage stress on the coating, causing the coating to crack and peel off. Preheating of the substrate surface can reduce and prevent the above adverse effects. But the preheating temperature should not be too high, so as not to cause the substrate surface oxidation and affect the bonding strength of the coating and the substrate surface. Preheat temperature is generally 80-90 ℃, commonly used to complete the neutral flame.
Pre-spraying a thin layer of metal prior to applying the working coating provides a clean, rough surface for the subsequent coating to improve the bond strength and shear strength between the coating and the substrate. Bottom bonding materials generally use ferrochrome nickel alloy.
Gear pump has a very large space for development.