a method of operating an ebpvd apparatus to deposit a ceramic coating on an article , such that the thermal conductivity of the coating is both minimized and stabilized . more particularly , the ebpvd apparatus is operated to perform multiple successive coating operations which together constitute a coating campaign . during the campaign , the surface temperatures of the articles being coated do not exceed about 1000 ° c . as a result of the combined heat transfer from the coating chamber to the articles being reduced during the course of the campaign , even though the temperature within the coating chamber continuously rises during successive coating operations of the campaign . ceramic coatings deposited at such relatively low temperatures exhibit lower and more stable thermal conductivities .