Detonation Thermal Spraying

　　Detonation thermal spraying developed by Dalian Maritime University that comparable with present the most famous D-Gun. The parameters for the coating and gases mass flow control using a computer and PLC system, good repetitively and dependability. In spraying process, the powder being inject appointed location in the gun tubular barrel, can be spraying low melting point metal, carbide and some of ceramics, the bond are over 7kg/mm2 for metal and carbide coating, and the porosity less than 1%.

Advantages of the Detonation thermal spray
Except for low porosities and high bond etc., as we have known for the coatings by Detonation thermal spraying and also shows following characteristic compared with the Plasma and HVOF thermal spray.

1. Economical lower running cost than HVOF
Consumption of oxygen is only 3~10% of that in HOVF (20 to 30 liters per minute), and not request using high-pressure gases; can be using vaporizing liquid oxygen, gas pressures (70 to 210kPa, 10 to 30 psi).
2. Powder and deposition rates
Can be sprayed multi-type powder from low melting point metal to high melting point of ceramics, powder particles size range at 10~100 micro. Powder deposition rates depend on the firing frequency and powder composition, ranging between 50 to 110grams/min.
3. Good coating for the mixing materials of the metal and ceramic
MCrAlY+Al2O3 coatings usually used for wear resistant at high temperature. The coatings consist of metal low melting point and ceramic high melting point. Detonation thermal spray can spray such as mixture powder, and the rates of metal/ceramic between powder and coatings almost sameness.
4. Spraying in the deoxidize atmosphere
The detonation gases can be controlled in deoxidize atmosphere by the regulating gases composition, be able to prevent oxidization of the metal particles during spraying and can spray boride and some of nitride powder.
5. The substrate temperature below 100 ℃ after sprayed, and with additional cooling it is possible to bring it down to room temperature.
Coating of MCrAlY+Al2O3
Coating of WC-12Co
Main performance of the equipment

Gun
1.Working gases: oxygen, acetylene, propylene and compressed air
2.Igniting frequency: 5~8 times/sec (adjustable)
3.Weight: 70kg

Controllers
1.Spraying parameters are digitally displayed and controlled by a easy-view touch-screen computer and PLC system.
2.Gas mass flow controller ensures the good repeatability of the coating.
3.Automatic monitoring system ensures D-gun’s safety in running.

Powder feeder
1.Powder feed rate is digitally displayed and can be stepless adjusted by electronic control.
2.Two liters powder capability ensures the long-term operating of D-gun.
3.High precision powder feeder has an error less than 1 g/min

Cooling system
1.Forced cooling device that can adjust the temperature of the cooling water is selectable to ensure the quality of the coating and the safety of D-gun.
2.Ordinary water circulation and cooling system is selectable to minimize the running cost.



Application of Detonation Spray

Hearth roll
process roll
Spindle
After finish