A thiadiazole metal deactivator (typically a
2,5-dimercapto-1,3,4-thiadiazole, or DMTD, derivative) is a multifunctional additive that protects non-ferrous metals — especially
copper and its alloys — from corrosion. It works by forming a protective chemisorbed film on copper surfaces, which:
1. Prevents the metal from catalyzing oil oxidation;
2. Stops copper being attacked by active sulphur from EP additives.
Thiadiazoles are used in industrial gear oils, hydraulic fluids, greases, metal-working fluids and engine oils. They are particularly important in formulations containing sulphur-based EP additives, where uncontrolled copper corrosion would otherwise be a problem. See our
anti-wear & EP additives.