COMPOSITE POWDERS FOR THERMAL SPRAYING

Composite powders of type “metallic alloy/refractory compound” are produced by the synthesis in technological combustion mode, followed by operations of milling and classification by fractions.

The following materials are used:

· metallic alloys:

based on iron - Fe, FeCr;

based on nickel - Ni20Cr, Ni40Cr, NiCrAl;

based on aluminum - Al, Al12Si;

intermetallides - NixAly, FexAly, TixNiy;

· refractory compounds: carbides - TiC, Cr₃C₂, Cr₇C₃, SiC P and their combinations.

Powders can be used for the spraying of corrosion and wear resistant protective coatings using plasma, high-velocity oxygen-fuel and detonation methods.

In comparison with conventional thermal sprayed mechanical blends and agglomerated powders, synthesized powder materials have the following advantages:

§ Fine volume distribution of a solid phase (size of refractory grains of refractory components is 0,5-10 μm);

§ High cohesion strength of a composite (cohesive bonds are formed in the process of synthesis during the interaction between refractory phase and metal (alloy);

§ Constancy of a phase composition of powder (independently on particles sizes), that enables:

- to increase the coefficient of material consumption 10 - 30%;

- to keep a phase compound of the composition during the spraying; орошки предназначены для нанесения защитных износо- и коррозионно

- uniform distribution of a solid phase within the coating volume.

Grade

Composition, wt. %

Melting point, °С

Coating hardness, HV

Characteristic features of coatings

Application

NCC-75

NiCr - basis 75%Cr₃C₂

1900

670-920

High abrasion and erosion resistance as well as high temperature corrosion resistance (up to 870°С).

Parts of energetic plants (boilers, turbines and combustion engine parts), forging rigging, crushing rollers, hot pressing matrixes, bearing inserts

and etc
.

NCT-55

NiCr - basis

55%TiC

2100

680-990

High abrasion and erosion resistance as well as air and salt corrosion resistance at temperatures up to 350°С.

Parts of energetic plants, gas turbine exhaust blades, surfaces of pump parts, inserts (bushes) of shafts and machine slide way, axles of chassis, brake arrangement of planes, compressor carriage and etc.

FCT-50

Fe - basis

50%TiC

1500

680-1300

High sliding abrasive wear resistance, ability to stand increased contact pressures.

Steel shafts, seats for bearings, pressing rigging operating with plastics, ring gaskets, plunger-pumps and etc.

ASCT-50

AlSi - basis

50%TiC

800

340-430

High abrasion and erosion resistance, as well as low temperature corrosion resistance on air, seawater and in a weakly acid media.

Parts and structures from aluminum and titanium alloys: fastening foot of rotor blades, screw blades of aircrafts, plane chassis, submarine feed screws, synchronizer rings, frictional disks, parts of a tread guiding armature and etc.

NAA-40

NiAl - basis

40%Al₂O₃

1600

350-575

High erosion resistance under elevated temperatures and low and high temperature corrosion resistance in the presence of chlorides. Coefficient of thermal expansion is close to steel ones.

Parts for energetic plants, production and processing of chemical threads; restoration and protection of salt-production equipment from corrosion and wear.