In the metallurgical industry, there are many kinds of rolls and conveying rolls that need wear-resisting strengthening or repairing, among which, the continuous annealing furnace bottom roll of cold rolled strip steel is an important one. Cold-rolled strip steel depends on a set of rollers in furnace turn the implementation work, general of temperature in the annealing furnace of 450 ~ 1200 ºC, under the high temperature furnace roller continuous conveying steel strip, steel strip surface oxide film or deposition reduction of iron filings and activation, generate Fe, Fe3O4 and FeO and other compounds, with the roller surface under the action of friction, produce very big extrusion stress, When the protective film of the roll surface is destroyed, the exposed active metal surface will produce solid phase welding with the activated iron powder under compressive stress, resulting in nodulation on the roll surface, destroying the original roughness of the roll surface, and the strip will be scratched by nodulation, affecting the surface quality.
Roll surface nodulation phenomenon, in fact, is adhesion wear. In order to reduce the loss caused by nodulation in the production of steel strip, nicR-Cr3C2 coating can be sprayed on the roll surface by supersonic flame. It has the characteristics of high temperature oxidation resistance, thermal shock resistance and wear resistance, and can make the furnace rod work continuously for a long time at high temperature, and can withstand periodic thermal shock. When the furnace low roller operating temperature exceeds 900ºC, a spray Co - based alloy.
In the metallurgical production line, a large number of rollers are used to transport all kinds of steel, which will wear out after long-term use and affect the quality of steel. The operating temperature of the conveying roller is relatively low, and its surface can be sprayed with Co based WC coating, which can work at 450ºC and has good wear resistance and comprehensive mechanical and mechanical properties.
Supersonic flame spraying has unique advantages in the spraying of carbide ceramics, and the metallurgical industry has a great demand for carbide cermet coating, so it has been widely used.
In addition, the sunken roller on the hot-dip galvanized line also needs to be protected by thermal spraying. The hot-dip galvanized sheet has good corrosion resistance, processing formability, weldability and environmental protection, and is widely used in various fields such as automobile, construction, household appliances and national defense. At present, most of the hot dip zinc unit of strip steel in the world's iron and steel enterprises use sunken roll device. The sunken roll and other parts in the molten zinc production line are immersed in the molten zinc solution at 450~480ºC, which is easy to be corroded by highly active zinc solution or precipitate Fe-Al-Zn intermetallic compound nodulation, resulting in pitting corrosion and pitting pit on the roll surface. Affect the surface quality of galvanized steel plate. In order to prevent the direct contact between liquid zinc and sunken roll from alloying corrosion reaction, resulting in coarsening of steel roll surface and affecting the quality of galvanized steel sheet, the surface of continuous galvanized sunken roll is generally sprayed for protection. The coating materials are WC-CO, MoT-Mo and Fe-Al thermal spray powder, etc. The corrosion resistance of WC-Co coating in zinc solution depends on its bonding phase. As the diffusion corrosion channel of zinc liquid in the coating is mainly along the cobalt-rich phase, when the bonding phase in the coating is mainly η phase (Co3W3C and Co6W6C, etc.), η phase can effectively prevent the diffusion of zinc liquid into the coating and delay the corrosion of zinc liquid on the coating. On the other hand, the particle size of WC and Co content in the coating also directly affect the corrosion resistance and service life of the coating. The coating with small WC grains and low Co content has higher wear resistance, while its corrosion resistance in Zn liquid is poor. Therefore, appropriate WC particle size and appropriate Co content should be selected to achieve better comprehensive performance. When WC grain size is 2-4 μm and Co content is 10% to 17%, the coating has the best performance.
Main performance indicators
1. Porosity is only 0.5%.
2, the microhardness of the coating is up to 1250Hv0.2,
3. The binding strength of the coating and the matrix is greater than 70MPa.
4, its service life can reach 40 ~ 50 days,
5, surface roughness: Ra0.2
Audited Supplier 
){kind=link}
){kind=link}