Thermal Fatigue Test Of PVD Coating

- Apr 04, 2018-

There is no corresponding standard for the fatigue test of PVD coating, but it can refer to the fatigue test method of thermal barrier coating.

In addition to meeting the general requirements of coatings, PVD coatings must also meet some special requirements.Thermal fatigue resistance is one of the important indicators. Because PVD coating often works at high temperature and it experiences high and low temperature repeatedly and bears the effect of persistent thermal fatigue stress. For example, the coating on the surface of the die casting die of the aluminum alloy must bear the effect of the alternating temperature of the constant temperature to 700 °C, which requires the coating with high thermal fatigue resistance to not fall off. Tests have used a variety of methods to determine the thermal fatigue resistance of thermal barrier coatings. The heating (cooling) methods include induction heating (compressed air cooling), induction heating (water vapor cooling), and electric furnace heating (water cooling), the way of the electric furnace heating (water cooling) is the opposite, and the advantages and disadvantages of the induction heating (water and gas cooling) are between the two.

This kind of test is mainly used for the comparison of thermal fatigue properties between different coating materials and different process, and the electric furnace heating (water cooling) method can achieve this goal completely.

Sample design is the key work of coating test. Whether the design of sample is reasonable will greatly affect the test results. The previous experiments show that because of the large stress concentration at the edge angle of the rectangular plate, and the thermal stress produced by the non-uniform heat of each part of the specimen during the test, the coating often destroyed near the edge angle. The cylindrical sample can avoid the above problems and is a more reasonable specimen.