Thermal spray powder|an application example in paper making machinery

1.Wear resistant coating

The WC coating calender with supersonic spraying shows better wear resistance than chilled cast iron, and the WC coating also has rolling contact fatigue strength of up to 8Gpa, which fully meets the rolling pressure of the calender roll. Due to the dense coating without holes, corrosion resistance is also better than electroplating roller surface, due to the fine and dense coating, the coating can be ground to a mirror finish.This kind of WC coating sprayed on the surface of ordinary steel rolls is especially suitable for the manufacture of super large calender rolls, and there is no casting defect of chilled cast iron. In addition, this coating can also be sprayed on the surface of the dewatering tank panel, and the wear resistance of only 0.15mm is enough to be several times better than stainless steel.

2.Hydrophilic coating

The use of oxyacetylene flame sprayed ceramic coating, used in the coating machine coating, water application roller, hydrophilicity is much better than the electroplating roller surface, water, feeding uniformity is good. This hydrophilic function of the coating is mainly due to the micro-pores of the sprayed ceramic coating, which has the ability to absorb water and enhance the wettability of the coating, and when the coating has a certain thickness, the capillary pores of the straight through the body can be eliminated, so the coating will not appear in a short period of time. Generally, the coating of 0.5mm thickness is enough to make the roller have a life of about three years. The ceramic coating ring can be sprayed on the surface of the steel roller, replacing the traditional stone roller, especially the large stone roller which is difficult to make.

3.Anti-stick coating

Both ceramic and cermet coatings have the characteristics of non-adhesion to unrelated substances, and can be used on the surface of the first drying roller in the drying area, which can effectively prevent the occurrence of adhesive. The wear resistance life of this coating is much greater than that of fluoroplastic anti-stick coating, and the anti-stick effect is no less than that of plastic coating.

4.Non-slip coating

Mo spray powder, as the most original thermal spraying material, has been widely used in paper machine rewinding rolls, and Mo is not an ideal non-slip material, because M. has self-lubricating properties. At present, in addition to some lack of lubrication conditions and need to lubricate friction parts (such as internal combustion engine piston rings) also use spray aluminum, Mo has been replaced in most cases by new spray materials. For large paper rolls, Mo powder by oxyacetylene flame spraying is often unable to reach high bonding strength because it cannot be preheated. However, the coating of M. powder with arc will oxidize the coating due to the high temperature. With ultrasonic spraying WC or NiCr alloy, not only can achieve the non-preheating construction of large workpieces, but also obtain a dense, delicate coated surface, and WC coating has a higher friction coefficient, far better than Mo coating anti-skid performance.

In short, the application of ceramics and cermet in paper making machinery is far more than the above, and better coatings are waiting for our development and utilization to meet the needs of a variety of complex working conditions.