limit of fire resistance 基本例句 耐火极限 The coatings film will be dilatated when contacted to fire, forming a high dense and microporous fire proofing layer to prolong the fire retardant limit of steel structures.由该涂料制得的涂层遇火发泡膨胀,形成具有一定厚度的密实微孔状阻燃层,从而提高了钢结构的耐火极限。