Development of Three-Dimensional Non-Contact Surface Profilometer and Application to Evaluation of Impact Erosion of Metal Matrix Composites
A three dimensional non-contact surface profilometer system which can measure a wide area (order of square milli-meters) with high resolution (sub micro meter) has been completed. This system can measure the surface topography in the atmosphere by means of a confocal wavelength displacement sensor. We examined the optimum measurement conditions and applied them to the evaluation of erosion properties of particle reinforced metal composites. As a result, a scanning speed of 1mm/s and sampling intervals of 0.5-15μm were found to the optimum conditions. In addition, we evaluated the differences of properties in composite materials with different volume fractions using this system. We conclude that our technique is useful in the evaluation of erosion properties of composite materials.
Evaluation of wear resistance of thin hard coatings by a new solid particle impact test
Abstract For the evaluation of tribological properties of thin hard coatings, several experimental techniques are normally used, such as scratch testing and testing against abrasive, erosive, and sliding wear, and fretting. In this paper, we propose slurry jet, a new type of solid particle impact test, in order to quickly evaluate wear properties of thin, single layered or multilayered physical vapor deposited (PVD) coatings. By slurry jet 1 μm alumina particles were impacted at high velocity perpendicular to thin PVD coatings of TiN, TiN/NbN, TiN/TaN, TiN/CrN, TiN/TiAlN deposited on a high speed steel (HSS) substrate material. The coatings proved to have much higher erosion resistance than the substrate material and, consequently, the wear rate increased significantly to the higher level of the HSS material when the coatings were penetrated. The maximum peak-to-valley roughness (Ry) of the eroded coatings was of the order of 0.1–0.5 μm, suggesting that the size of the detached particles was of the same order. The ranking of erosion resistance and correlation to the mechanical properties, such as hardness and critical normal load obtained by scratch testing are discussed. We conclude that the proposed evaluation test is fast and easy to accomplish. It generates reproducible results and is very sensitive to the quality of the coating. Thus, it can preferentially be used as a screening test when evaluating coatings and coated materials. In particular, the interface strength of multilayered coatings with very thin lamella can be assessed. For the coatings included in this study, the TiN/TiAlN proved to have the highest erosion resistance, whereas the TiN/CrN was the worst.
The performance of marine coatings and pipe materials under fluid-borne sand erosion
A program of tests is described in which pipe materials and steel substrates with various coatings were subjected to fluid-borne sand particle erosion conditions. Sand-water slurry jets were used at velocities between 2–30 m/s and at a jet impingement angle of 90° to create a range of erosive conditions to evaluate the performance of the pipe materials carbon steel AISI 1020, stainless steel AISI 316. Cupro-Nickel 90/10, medium density polyethylene and glass reinforced plastic test coupons. Further tests at an impingement angle of 30° and at 10 and 20 m/s velocity compared the performance of the carbon and stainless steels with various polymeric, metallic and ceramic coatings. Flexible polyurethane seems to have promise for future use in fluid-borne sand particle erosion environments. The erosion mechanisms of flexible polyurethane have been identified as micro-cutting at low angle impingement and fatigue/crack propagation at normal impact.