The effect of PTFE addition on mechanical and anti-corrosion properties of coating of heat exchangers

Abstract

Through adjusting the concentration of poly tetra fluoroethylene (PTFE) particles of the Ni–Cu–P composite coatings, the Ni–Cu–P-PTFE composite coatings with different PTFE concentration were obtained. Further experiments and studies demonstrate that the elasticity modulus and the microhardness of Ni–Cu–P-PTFE coating are inversely proportional to the content of PTFE particles. Meanwhile, adhesion strength between Ni–Cu–P-PTFE coatings and matrix is not just influenced by the content of PTFE particles in the coatings, but also by the surfactant in the bath. Furthermore, the Ni–Cu–P-PTFE coating performs well corrosion resistance. However, due to the increase of pores in the coating caused by the increasing number of PTFE particles, the thermal conductivity and the corrosion resistance, as well as the mechanical properties, of the coating will reduce correspondingly. So when the Ni–Cu–P-PTFE composite coating is utilized, PTFE content in the plating solution should be kept within an appropriate range rather than providing a high PTFE condition. The principal advantages of PTFE particles exerted on the ternary Ni–Cu–P composite coating refer to the characteristics of no adhesion, as well as better corrosion resistance. Therefore, the Ni–Cu–P-PTFE composite coatings can be helpful for the bourdon tube heat exchanger and surface of flexible equipment.