Structurally Integrated Coatings for Wear and Corrosion

Wear and corrosion of structures cuts across industries and continues to challenge materials scientists and engineers to develop cost effective solutions. Industries typically seek mature technologies that can be implemented for production with rapid or minimal development and have little appetite for the longer-term materials research and development required to solve complex problems. The collaborative work performed in this project addressed the complexity of this problem in a multi-year program that industries would be reluctant to undertake without government partnership. This effort built upon the prior development of Advanced Abrasion Resistant Materials conduct by Caterpillar Inc. under DOE Cooperative Agreement No. DE-FC26-01NT41054. In this referenced work, coatings were developed that exhibited significant wear life improvements over standard carburized heat treated steel in abrasive wear applications. The technology used in this referenced work, arc lamp fusing of thermal spray coatings, was one of the primary technical paths in this work effort. In addition to extending the capability of the coating technology to address corrosion issues, additional competitive coating technologies were evaluated to insure that the best technology was developed to meet the goals of the program. From this, plasma transferred arc (PTA) welding was selected as the second primary technology that was investigated. Specifically, this project developed improved, cost effective surfacing materials and processes for wear and corrosion resistance in both sliding and abrasive wear applications. Materials with wear and corrosion performance improvements that are 4 to 5 times greater than heat treated steels were developed. The materials developed were based on low cost material systems utilizing ferrous substrates and stainless steel type matrix with hard particulates formed from borides and carbides. Affordability was assessed against other competing hard surfacing or coating techniques, balanced with overall materials performance. State-of-the-art design and simulation capabilities were used to guide materials and process refinement. Caterpillar was the lead of the multi-partner collaborative project. Specific tasks were performed by the partners base on their unique capabilities. The project team was selected to include leaders in the field of material development, processing, modeling, and material characterization. Specifically, industrial members include the suppliers Deloro Stellite and Powder Alloy Corporation., who provided the experimental alloys and who aided in the development of the costs for the alloys, the Missouri University of Science and Technology and Iowa State University, who provided help in the alloy development and material characterization, QuesTek Innovations, a small company specializing the microstructural modeling of materials, and the DOE laboratories, Oak Ridge National Laboratory and National Energy Technology Laboratory (Albany), who provided unique coating process capability and wear characterization testing. The technologies developed in this program are expected to yield energy savings of about 50% over existing technologies, or 110 trillion BTUs per year by 2020 when fully implemented. Primary applications by Caterpillar are to replace the surface of machine components which are currently carburized and heat treated with new cladding materials with double the wear life. The new cladding technologies will consume less energy than carburizing. Thus, nearly 50% energy savings can be expected as a result from elimination of the heat treat process and the reduce wear of the materials. Additionally, when technologies from this project are applied on titanium or other non-ferrous substrates to make lighter weight, more wear resistant, and more efficient structures, significant fuel savings can be realized. With the anticipated drastic reduction in cost for refining titanium-containing ores, the usage of titanium alloys in earthmoving and related machinery is expected to increase multiple folds in the next decade. A major technical hurdle associated with the implementation of titanium alloys for heavy machinery is that of overcoming poor wear resistance. Proof of concept of the technologies developed in this project has been demonstrated by both laboratory testing of coupons and field testing of selected components. Further development will be required in order to have fully validated materials and process for production introduction and several technical hurdles remain to be addressed particular for use of the arc lamp fusing technology. The current project has reduced the risk of failure and provided sufficient data to encourage further investment by industry