Aluminum Nitride is a metalic substance used in place of a coil in some toppers due to it’s very long service life (up to 600,000 cycles according to one manufacturer). Not much is known about the effects of using aluminum nitride over more common heating elements however the MSDS information for it is not promising:
“Contact with acids may generate flammable hydrogen gas. Phosgene gas may be produced if chlorinated vapors are present.”
“INHALATION: Acute: May be an irritant and possible corrosive to the nose, throat and mucus membranes. May cause chemical pneumonia, chemical bronchitis and pulmonary edema. Ammonia gas may cause irritation to the nose and throat, dyspnea, bronchia spasms, chest pain, pulmonary edema and pink forthy sputnum. Chronic: May cause pulmonary fibrosis. Repeated or prolonged exposure to ammonia gas may cause swelling of the mouth and throat to the point of asphyxiation, permanent injury or death.”
You can find the MSDS for aluminum nitride here and decide for yourself… I personally was about to buy an RDA using aluminum nitride as the heating element and have now decided to hold off and stick to my normal fused clapton builds for now.