PTFE is a white crystalline polymer with excellent chemical stability and thermal stability. It can work for a long time at temperatures up to 250 ° C. It has low friction coefficient and excellent lubricating properties. Its dynamic friction coefficient Only 0.04, therefore, PTFE sheet has a wide application prospect in the repair of lathes.
At the same time, the PTFE sheet also has a typical hard tackiness. This is because the binding energy of the C-C bond and the C-F bond in the molecular chain of the PTFE is large, and the intramolecular bonding is firm, so that the binding force of other molecules is weak. The fluorine atoms in the material shield the carbon atoms, making it difficult for other active molecules to penetrate and bond. Therefore, the surface of the PTFE sheet is a typical low-energy surface with a surface tension of only 1.85×10-2 N/m, which is also the smallest among the known solid materials, and the surface tension of the metal is generally 1×10-1 N/m, so it It is a typical hard-to-bond material.
In order to bond PTFE to metal, the main method currently used is to use nano-naphthalene activity method to activate the surface of the material, and remove the fluorine atom on the surface of the PTFE sheet to increase the surface tension to 3×10-1N/m, with good adhesion. The surface-activated PTFE sheet has good lubricity and wear resistance, high bonding strength and convenient maintenance, and is widely used in the repair of lathe guide rails, and has objective economic benefits. The bonding process is also relatively simple, mainly to bond the activated PTFE sheet to the carriage of the lathe rail. According to the general bonding method, the contact surface is first cleaned and then bonded, and the pressure is cured at room temperature. It can be processed and assembled in 48h, and its bonding strength can reach 10MPa or more.