Dr. Thomas Mebrahtu is the global R&D manager for metals processing and atmospheres at Air Products, where he leads the development of gas-based applications for the global metals processing and back-end electronics packaging markets.
The primary cooling method for most HVOF thermal spray operations is forced air cooling using compressed air jets. However, the oxygen, residual moisture and hydrocarbons in the cooling air are often detrimental to the coating quality. Because air cooling alone is usually insufficient, interpass cooling breaks must be introduced into the process, which reduces productivity. In addition, when the spray gun is moved away from the part during these cooling breaks, it continues firing, resulting in wasted feed powder and process gases. A new nitrogen cooling technology overcomes these problems, thereby improving HVOF coating quality and reducing costs.
