Study On Ferromagnetic Shape Memoryalloy Reinforced Silver Contact Materials

Relay is one of the most widely used in the automotive electronic components. Inorder to meet the needs of increasing power consumption of the vehicle’s electrical system,the automotive electrical system voltage of12V or14V will now upgrade to42V.Traditional relay arc will affect more and more, it brings serious damage to the relay.Researching new contacts and contact materials is imperative. Ferromagnetic shapememory alloy as a new generation of smart materials whose unique magnetic, heat-inducedmemory effect has broad application prospects.In this paper, we select Co-Ni-Ga ferromagnetic shape memory alloy as thebreakthrough point to explore the next generation of suitable42V working voltage contactmaterials, intending to use its ability of phase transitions in high temperature to reduce thecontact temperature endothermic, weakening arc erosion. Co-Ni-Ga alloy has a generallytwo-phase (β+γ) coexistence equilibrium organization.Alloy composition obtained throughexperiments with a pure crystal structure of the martensite:Co40Ni30Ga30、Co42Ni28Ga30、Co44Ni26Ga30、Co45Ni26Ga29. Respectively, in the endothermic reaction of452°C,414°C,365°C and460°C. The content of the alloy is mass fraction5%,10%,15%.When Contentis5%, the alloy does not play a significant role. Content of10%, the arc welding skills andability to resist corrosion resistant contacts have been strengthened. Ag-Co42Ni28Ga3010%type contacts lost the minimum quality by arc erosion. Content of15%, the maximum lossof quality.The deep pits formed on the surface of the anode contacts. Polar shift qualitycontacts are short arc transfer case that anode contact by serious erosion of the cathode arccontact, some contact material transferred from the anode to the cathode, causing what thesurface of the convex hull of the cathode contact form.The influences of same Co-Ni-Ga alloy composition and different content on theelectrical properties on the contacts are significantly different. The same content, differentdegrees of contact erosion Co-Ni-Ga alloy composition varies with the phase transitiontemperature, showing changes in more regular. At low temperature section:365~414°C, themoving contact mass loss Δm decreases with increasing temperature; In the warm sectionof414~452°C, Δm increases with increasing temperature until it reaches the maximum lossamount; In the high temperature section of452~460°C, Δm declines sharply as thetemperature rises. Similar mass loss happens when the endothermic temperatureapproximates. We can find the best alloy composition as the contact material in point of the phase transition temperature according. This effect on the choice of new contact materialhas a guiding role.