IMPROVED EROSION RESISTANCE FOR THERMAL BARRIER CERAMIC COATING PROTECT

The erosion wear resistance of Ni base super alloy (Monel 400) can be improved by thermal sprayed coatings produced by the high velocity oxygen fuel (HVOF). In this work, (Monel 400) is coated with two different types of coatings, the first one is Al2O3+5% TiO2 and the second is Al2O3 +15% (7-8YSZ), these layers were made of 350-400 μm as top coat, pre-sprayed with 50-100 μm of 4NiCr5Al as a bond coat To study the erosion wear behavior of the coatings, erosion test apparatus was designed according to ASTM G-76 also a plan of experiments based on the Taguchi technique is used to acquire the erosion test data in a controlled way. An orthogonal array and signal-to-noise ratio are employed to investigate the influence of the coating materials, impingement angle and stand-off-distance on the erosion rate. The study reveals that the coating materials is the most significant factor influencing the erosion wear rate. Al2O3 +15% (7-8YSZ) has higher wear resistance than Al2O3+5% TiO2, Porosity influences their performance when subjected to wear (loss of thickness increased as the porosity increased), The measurement of hardness before and after the wear tests indicates that there was no significant change in either the metal or the coated samples at 3000C for 1 hr. To assess adherence index, porosity and the hardness for the Al2O3 +5% TiO2 coating are 84%, 9% and 454 HV0.3 respectively while for the Al2O3 +15% (7-8YSZ) coating are 80.1, 17% and483 HV 0.3 respectively.