Development of superheat-resistant enameled wire

With a view to developing superheat-resistant enameled wires capable of continuous service at 300°C or higher temperatures we studied the applicability of synthetically obtained borosiloxane resins whose chemical structure suggested excellent heat resistance.¹ As a result, a solvent-soluble varnish made up mainly of the borosiloxane resins was obtained, and through use of this varnish two types of superheat-resistant enameled wires have been developed. It has been demonstrated in a series of tests that these wires are by far more heat-resistant than the conventional heat-resistant polyimide wire and are capable of prolonged service at 450°C or higher temepratures.