How H2+N2 mixed gas from ammonia crackers prevents oxidation during annealing, brazing, and sintering. Used across automotive, aerospace, and tool manufacturing.
When metals are heated above 700C in air, they oxidize rapidly — forming scale, discoloration, and surface defects. Heat treatment processes like bright annealing, brazing, and sintering require a protective or reducing atmosphere to maintain clean, oxide-free surfaces.
The most cost-effective atmosphere for most heat treatment applications is an H2+N2 mixture (typically 75% hydrogen + 25% nitrogen) — produced on-site by an ammonia cracker. This gas prevents oxidation (N2 component) and reduces any existing oxide (H2 component).
1. Feed: Liquid ammonia (NH3) is vaporized and preheated.
2. Crack: NH3 passes through a nickel catalyst at 800-850C, decomposing into N2 + 3H2.
3. Output: 75% H2 + 25% N2 mixed gas — delivered directly to the heat treatment furnace.
4. Post-treatment (optional): Residual NH3 (<5 ppm) removed with molecular sieve adsorber for sensitive applications.
Liquid ammonia costs significantly less than bottled H2/N2 mixtures — typically 50-65% cost reduction for heat treatment atmospheres.