1. Selection by Temperature Range (Core Matching)
0~1100℃: Type K thermocouple (Nickel-Chromium/Nickel-Silicon) – vacuum-resistant, cost-effective, suitable for conventional vacuum quenching/tempering.
1100~1600℃: Type S thermocouple (Platinum-Rhodium 10/Platinum) – high-temperature oxidation resistance, suitable for high-temperature vacuum annealing/brazing.
1600~1800℃: Type B thermocouple (Platinum-Rhodium 30/Platinum-Rhodium 6) – excellent stability under vacuum, suitable for ultra-high-temperature ceramic/alloy processing.
2. Key Supplementary Requirements
Vacuum Compatibility: Choose thermocouples with organic-free insulation and metal protection tubes (e.g., molybdenum, tantalum tubes) to avoid gas release that contaminates the vacuum.
Atmosphere Adaptation: Use platinum-rhodium series for hydrogen/inert atmospheres; prioritize Type K for carbon-containing atmospheres (vacuum carburizing) to prevent platinum poisoning.