An Integrated Investigation Approach for Coating Temperature Measurement and Control During Plasma Spraying
- PDF / 523,140 Bytes
- 12 Pages / 593.972 x 792 pts Page_size
- 57 Downloads / 176 Views
Haiou Zhang, Weisheng Xia, Guilan Wang, Yunzhen Yang, and Yang Zou (Submitted June 29, 2006; in revised form August 27, 2007) An integrated investigation approach for temperature measurement and control of plasma sprayed coating is presented in this paper. It is based on infrared (IR) pyrometry combined with specific robot scanning trajectories. The temperature evolution was continuously detected and recorded during preheating, spraying, and cooling stages. Then the two specific factors, periodic average temperature and periodic standard deviation, were adopted to evaluate the temperature variation and the fluctuation of the thermal cycle relevant to one spraying period. These two factors were successful in describing the temperature variation during experimental processing sets. Moreover, the influence of processing parameters of Z-type robot spray trajectory, including spray distance, scanning velocity, and scanning step on coating temperature is experimentally researched and explained reasonably by comparing the two factors.
Keywords
atmospheric plasma spray, diagnostics, IR pyrometry, process control, process monitoring, robot trajectory, spraying parameters, substrate/ coating temperature
1. Introduction The temperature and velocity of sprayed particles prior to their impact onto the substrate surface and the temperature history of substrate/coating are important parameters influencing the formability and quality of thermally sprayed coatings (Ref 1-4). However, the relationship between the temperature history and the properties of thermal sprayed coatings is still unclear. It has been emphasized that the monitoring of particle parameters at impact and coating temperature is a key issue for coating quality, reliability, and reproducibility (Ref 5, 6). Therefore, many efforts have been devoted to research on the monitoring and control of coating temperature. To the knowledge of the authors, coating temperature can be measured during spraying by using various means: thermocouples (Ref 7-9), infrared (IR) pyrometry (Ref 10-15), pulse thermography (Ref 16), infrared thermal cameras (Ref 11, 13, 17), and other specially designed
Haiou Zhang and Weisheng Xia, State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science & Technology, Wuhan 430074, China; and Weisheng Xia, Guilan Wang, Yunzhen Yang, and Yang Zou, State Key Laboratory of Material Processing and Die & Mould Technology, Huazhong University of Science & Technology, Wuhan 430074, China. Contact e-mail: [email protected]
Journal of Thermal Spray Technology
infrared thermal nondestructive testing (NDT) scanning systems (Ref 18). Although thermocouple measurement is a regularly applied and simple method that works well in a wide temperature range, the lack of good thermal contact to the surface being measured still remains an unresolved problem and leads to formation of the temperature gradients between thermocouple and sample. During the on-line temperature monitoring of plasma sprayed parts, thermocouples
Data Loading...
