the instant disclosure relates to an improved heating chamber of a heating device having a non - reactive surface layer . the heating chamber includes at least one metal layer and at least one non - reactive disposed thereon . the improved heating chamber is protected against reacting chemically during the thermal treatment process , and has better anti - corrosion capability . the heating chamber is also protected against cracking . therefore , the service life of the heating chamber is extended . a heating device having improved heating chamber and at least one method of forming the non - reactive layer are also disclosed .