The Properties of NiCrTi Wire Used For Boiler Tubes

The problems such as high temperature oxidation, sulfide corrosion, dust scour and so on of boiler four pipes (cold water wall tube, super heater tube, re-heater tube, economizer tube) of thermal power plant seriously affect the long-term normal operation of thermal power plant. The tubes of the combustion boiler and the black liquid boiler of the paper-making industry are all subjected to high temperature oxidation, sulfide corrosion and erosion in the working condition. According to the problem we can use high-chromium-nickel alloy coating wire NiCrTi, NiCrTi coating effectively prolongs the service life of the pipeline. Specific performance is as below:

1  The NiCrTi coating can form a layer of high density of Cr2O3 oxide film at high temperature, anti-sulfide corrosion resistance of carbon steel 60 times.

The coating of high chromium-nickel alloy wire is firstly subjected to the preferential oxidation of Cr in the hot corrosion of the sulfide, forming Cr2O3 oxide. When the content of chromium reaches more than 40%, a dense layer can be formed. The complete oxide coating can prevent the corrosive media into the coating matrix, finally the substrate is fully protected.

2  NiCrTi Coating can resist corrosion of corrosive (sulfur, vanadium) gases generated in boiler operation at high temperatures close to 980℃.

3  Average denudation rate <0.0127mm / year, the life of tubes can be extended to more than 7 years.

4  NiCrTi coating and carbon steel have relatively similar thermal expansion coefficient, so it’s good to prevent the coating off.

Preparation of NiCrTi coating by arc spraying is a good method to improve the service life of the four tubes of the boiler. It has the similar coefficient of linear expansion coefficient with the tubes of the boiler. It can form metallurgically with the substrate and form a dense, uniform and complete high temperature anti-corrosion, high temperature anti-erosion coating.

5  Coating Of NiCrTi can be a good self-bonding effect with the substrate.

6  Coating of NiCrTi porosity less than 1%, no through-hole.

7  During working, we can accurately measure the coating thickness because of the non-magnetic of NiCrTi coating.

8  NiCrTi coating compares with other spraying methods, it has the advantages of economy, flexibility, reliability, high efficiency and less pollution etc.