Deposition of Electrically Conductive Coatings on Castable Polyurethane Elastomers by the Flame Spraying Process
- PDF / 1,817,759 Bytes
- 12 Pages / 593.972 x 792 pts Page_size
- 105 Downloads / 262 Views
H. Ashrafizadeh, A. McDonald, and P. Mertiny (Submitted April 13, 2015; in revised form November 17, 2015) Deposition of metallic coatings on elastomeric polymers is a challenging task due to the heat sensitivity and soft nature of these materials and the high temperatures in thermal spraying processes. In this study, a flame spraying process was employed to deposit conductive coatings of aluminum-12silicon on polyurethane elastomers. The effect of process parameters, i.e., stand-off distance and air added to the flame spray torch, on temperature distribution and corresponding effects on coating characteristics, including electrical resistivity, were investigated. An analytical model based on a Greens function approach was employed to determine the temperature distribution within the substrate. It was found that the coating porosity and electrical resistance decreased by increasing the pressure of the air injected into the flame spray torch during deposition. The latter also allowed for a reduction of the stand-off distance of the flame spray torch. Dynamic mechanical analysis was performed to investigate the effect of the increase in temperature within the substrate on its dynamic mechanical properties. It was found that the spraying process did not significantly change the storage modulus of the polyurethane substrate material.
Keywords
coating characteristics, dynamic mechanical analysis, electrical resistance, flame spraying, polyurethane elastomer
1. Introduction The application of polymer-based materials in industrial equipment has become more prevalent due to their excellent mechanical and physical properties. Industry sectors with strong growth of polymeric materials include aerospace, oil/gas, and mining (Ref 1-8). The high strength-to-weight ratio of polymeric materials is the main driver for their use in the aerospace industry (Ref 1-3), while their excellent corrosion properties are advantageous for the oil/gas industry (Ref 4, 5). The type of polymeric material considered in the present study is polyurethane (PU), which high resistance to tear, oxidation, and humidity makes it attractive for use in the oil and gas and mining industries (Ref 6-8). On the other hand, the low thermal conductivity and high electrical resistivity of most polymers have limited their use in elevated temperature environments and/or where electrical conductance is required. Metallization of polymeric materials by the deposition of conductive coatings is a possible means to augment the effective thermal and electrical conductivity of a polymeric material. Metallic coatings may also H. Ashrafizadeh, A. McDonald, and P. Mertiny, Department of Mechanical Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada. Contact e-mail: [email protected].
Journal of Thermal Spray Technology
Nomenclature
A, B k L n q00 AVG t T x
Constants describing the back temperature of the substrate (T = At + B) Thermal conductivity (W/mÆK) Substrate thickness (m) Summation index Average heat flux (W/m2) Time (s) Temperature (C) Coordina
Data Loading...
