| Abstract: |
Geothermal is one of the most under-utilized renewable sources due to high investment costs and long development cycle. A major cost for geothermal operations is drilling, where cost can increase due to increased drilling depth, increase in tripping times, harsher environments, etc. During drilling, Down-the-Hole (DTH) hammers break the rock through repetitive impact and cuttings are removed via a high-velocity fluid. The main failure mechanism of hammer parts is found to be erosion and wear. To protect drilling equipment, various coating technologies have been applied. Selection of appropriate coatings should decrease drilling times, due to longer lifecycles. High velocity oxygen fuel spraying is one of the most popular technique to deposit thick coatings. Its lower flame temperature and high speed can result in dense and good adhered coatings. This paper discusses the deposition of cermet and alloy coatings using gas and liquid fuelled high velocity fuel spraying technique and their performance in simulated geothermal drilling environment. The properties of the deposited coatings in terms of microstructure, porosity, hardness, adhesion/cohesion strength, and erosion-corrosion resistance have been studied and the performance are compared with selected benchmarking steels used in geothermal drilling. Based on the findings of this study, recommendations are made for HVOF coatings that can be potentially used in geothermal applications.
This project has received funding from the European Union's Horizon 2020 research and innovation programme. Grant agreement 815319.
|
|
