What are the properties and application characteristics of nickel-aluminum intermetallic powder

       Nickel powder and aluminum powder are compounded or mixed. Around the melting temperature of aluminum powder, a strong exothermic reaction occurs, forming Ni-AI intermetallic compounds. The nickel-aluminum coating has high bonding strength with the substrate, and is the most important bonding coating material in the field of thermal spraying.



    1. Nickel-aluminum (Ni-Al) self-bonding composite powder

    Each particle of the nickel-aluminum composite powder is composed of fine nickel powder and aluminum powder, and its mass ratio is Ni:Al=80:20, Ni:Al=90:10, and Al:Ni=5:95. The resulting coating has the following characteristics:

    1) The bonding strength with the matrix is high, and it has certain metallurgical bonding properties;

    2) The sprayed nickel-aluminum coating has a very rough surface, which provides an ideal rough surface for further spraying;

    3) The thermal expansion coefficient of the coating is 12.6x10-6k-1 (25℃~535℃), which is similar to that of most steels;

    4) The coating has good high temperature strength and impact toughness, stable chemical properties and good high temperature oxidation resistance. It can be directly used for the bonding bottom layer of high temperature oxidation resistant coating or high temperature resistant ceramic surface coating below 815℃.

    5) The nickel-aluminum coating is non-magnetic and has good electrical conductivity.

    Nickel-aluminum composite powder, recommended as a self-bonding base material for the following materials: carbon steel, stainless steel, hardened alloy steel, nitrided steel, monel, nickel-chromium alloy, cast iron, cast steel, magnesium, aluminum, Titanium and Niobium. Not recommended as a bonding primer for copper alloys, molybdenum and tungsten.

    2. Nickel-chromium-aluminum (NiCr-Al) composite powder

    Nickel-chromium-aluminum composite powder is a self-adhesive and high-temperature oxidation-resistant composite powder developed on the basis of nickel-chromium heat-resistant alloy powder. Its structure is aluminum-coated nickel-chromium type. The sprayed nickel-chromium-aluminum coating is similar to the nickel-chromium coating, but with higher bonding strength, not only has excellent resistance to high temperature oxidation, but also has good thermal shock resistance and peeling resistance. The machinability of the coating is good and can be processed with ordinary tools.

    3. M (Ni, Co)CrAlY alloy powder

    This powder is based on the nickel-chromium-aluminum composite powder with a small amount of rare earth element yttrium (Y) added, and the heat resistance of the alloy is significantly improved. It can prepare high temperature oxidation resistant coating and high temperature gas erosion resistant coating used in the temperature range of 1000℃~1150℃; the bonding bottom material of the surface layer of high temperature thermal barrier ceramic coating in the temperature range of 1000℃~1300℃. It is used as the bonding bottom layer of the thermal barrier ceramic coating surface layer for aero-engine compressor blades (high temperature stage), engine combustion chamber, jet nozzle and rocket tube, gas turbine combustion chamber, etc.