Provided is a heat treatment apparatus that even when annealing SiC at high temperature, can exhibit a low heat capacity and perform uniform heating. The parameters, which determine the laser pulses and the cut lines, are synchronous in relation to the laser pulses and are continually modified along the closed cut line. The EVOH powder coating composition of the present invention forms a coating film having good uniformity when applied to a substrate as powder coating, even when it contains 1 part by weight or more water relative to 100 parts by weight of EVOH resin.