Yes, itâ€s a close enough substitute for a heat diffuser. A cast-iron skillet will evenly spread the heat throughout the bottom of the cooking vessel youâ€re using and treat the ingredients to a fair distribution of heat. This is because the cast iron material itself is a great heat conductor. However, with regular use, the surface of your cast iron skillet can erode out of its protective coating and penetrate the material to cause abrasive damage. So, to avoid this from happening, use this alternative sporadically.