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 erosive wear resistance of TiN coatings by a slurry jet impact test
Abstract In this paper, it is proposed to use a new type of solid particle impact test (slurry jet) to swiftly evaluate wear properties of thin, single layered or multilayered coatings. By the slurry jet, 1.2 μm alumina particles were impacted at high velocity perpendicular to thin PVD coatings of TiN deposited on high speed steel substrate materials under various substrate temperatures. Since the coatings have a much higher wear resistance than the substrate material, the wear rate increases significantly to the higher level of the HSS material when the coatings are penetrated. This is utilized in the quantification of the assessment of coating wear. A ranking of wear resistance and correlations to the coating surface hardness measured by nano-indentation tests, and coating morphology and structures are given and discussed. The TiN deposited under the highest substrate temperature proved to have the highest wear resistance although it had a relatively low hardness. The wear rate of the TiN coatings varies with the orientation of grains, that is, the {1 1 1} orientation that dominates for the high temperature deposition shows a higher wear resistance than the {1 0 0} orientation, which corresponds with the cleavage fracture behavior. Thus, it can be recommended as a screening test when evaluating coatings and coated materials.
An approach to elucidate the different response of PVD coatings in different tribological tests
Abstract In this paper, the different performances of duplex (i.e. with a prior plasma nitriding treatment) and non-duplex PVD coatings in micro-abrasive wear tests and impact tests are discussed, taking into account some key properties, such as nanohardness ( H ), elastic modulus ( E ) and the H / E ratio. The nanohardness and elastic modulus of the coatings were determined by nanoindentation and were characterised by means of several analytical methods, such as glow discharge optical emission spectroscopy (GDOES), X-ray diffraction (XRD), surface profilometry, Knoop hardness measurements, scratch tests and scanning electron microscopy (SEM). Similar H / E ratios were found for all coatings under investigation. Duplex (Ti,Al)N coatings exhibited the best wear resistance in micro-abrasive wear tests. The results obtained in such tests suggested the occurrence of abrasive wear by plastic deformation, with the hardest coatings displaying the lowest wear rates. The highest wear rates were recorded for duplex and non-duplex Cr–N coatings. Conversely, a duplex Cr–N coating exhibited the best performance in impact tests using a tungsten carbide ball. The duplex Cr–N coating displayed the lowest elastic modulus among all coatings tested, which can be attributed to the presence of a small amount of α-Cr metallic phase. This coated system also showed the smallest difference between the substrate and coating elastic moduli, indicating that low elasticity mismatch between the coating and substrate is desirable for achieving good performance in impact tests. The differing behaviours exhibited by duplex (Ti,Al)N and Cr–N coatings in different tribological tests reveal the importance of selecting the best coating for a given tribological application.