Optimization of spraying parameters and deposition mechanism of Sr_0.9(Zr_0.9Yb_0.05Y_0.05)O_2.85 TBCs by SPS

Abstract

Optimization of spraying parameters and deposition mechanism of Yb–Y‐modified SrZrO₃ [Sr_0.9(Zr_0.9Yb_0.05Y_0.05)O_2.85, SZYY] thermal barrier coatings (TBCs) by suspension plasma spraying (SPS) have been investigated. An orthogonal test scheme of “four factors and three levels” was created using a design of experiment software. The optimal spraying parameters were finally determined as 58 mm for spraying distance, 12 L/min for atomizing gas flow rate, 325°C for preheating temperature, 35 mL/min for suspension injection rate, 700 mm/s for horizontal movement speed, 1.5 mm/step for vertical movement step size, and 15 wt.% for solid content. The cross section of the SZYY coating is a columnar‐like crystal with some vertical cracks. The surface of the coating has the shape of a cauliflower. The deposition mechanism of SZYY coating is as follows: (1) Individual particles and smaller aggregates are deposited to form uneven particle hemispheres or ultrafine thin coatings. The smaller aggregates form small lamellar structures or small unmelted aggregates. (2) An individual particle and a small agglomeration form a large agglomeration, one part of which forms an individual particle and a small agglomerate, and the other part forms a large lamellar structure and an agglomeration structure.