While graphite hot zones have improved and gained more popularity over the years, all-metal hot zones have maintained their industrial demand as a method of offering a clean working environment and a low probability of producing contaminated parts. These important characteristics of the molybdenum-stainless steel hot zones have been crucial to produce parts made of super alloys like Titanium, Hastelloy, and Tungsten.
So, how do you know if an all-metal hot zone is the answer for you?
- If your process has zero tolerance for incidental dust or dirt, which is common for products used in the medical industry.
- Consider how your materials react with carbons in a graphite furnace. Graphite dust can lower melting temperatures which could lead to an adverse effect – including possible eutectic reactions (see temperature chart at the bottom of the page).
- Should your metals or alloys require high temperatures and ramp rates, an all-metal hot zone can perform at levels beyond a graphite hot zone. All-metal hot zones are capable of reaching temperatures above 2,400 °F (1,315 °C) and heating up at a maximum ramp rate of 75 °F (41 °C) per minute.
- If your materials require a tight tolerance of temperature uniformity, all-metal hot zones are capable of maintaining a uniformity range of ± 5 °F (3 °C). By AMS 2750G standards, a furnace within this range is defined as a class 1 furnace and provides the least temperature variation in the work zone.
Molybdenum
Quick Facts:
Symbol: Mo
Atomic Number: 42
Melting Point:
4753 °F (2623 °C)
Extracted from the ore, Molybdenite, which was often mistaken for graphite or lead.
Name derived from the Ancient Greek word, molybdos, meaning lead.
Both graphite and all-metal hot zones have distinct capabilities and advantages. To best find out which hot zone will work for your process, contact your regional sales or service representative, or fill out our online form.
Maximum Temperatures (°F) That Materials are Compatible Under Vacuum
| W | Mo | Al2O3 | BeO | MgO | SiO2 | ThO2 | ZrO2 | Ta | Ti | Ni | Fe | C | |
| W | 4,600 | 3,500 | 3,300 | 3,200 | 2,500 | 2,500 | 4,000 | 2,900 | 2,300 | 2,200 | 2,700 | ||
| Mo | 3,500 | 3,500 | 3,300 | 3,200 | 2,500 | 2,500 | 3,450 | 3,450 | 3,500 | 2,300 | 2,300 | 2,200 | 2,700 |
| Al2O3 | 3,300 | 3,300 | 3,300 | 3,300 | |||||||||
| BeO | 3,200 | 3,200 | 3,200 | 2,500 | 3,200 | 3,200 | 2,900 | 3,200 | |||||
| MgO | 2,500 | 2,500 | 2,500 | 2,500 | 2,500 | 2,500 | 2,500 | 2,500 | |||||
| SiO2 | 2,500 | 2,500 | 2,500 | 2,500 | |||||||||
| ThO2 | 4,000 | 3,450 | 3,200 | 2,500 | 3,600 | 4,000 | 3,450 | 3,600 | |||||
| ZrO2 | 2,900 | 3,450 | 3,200 | 2,500 | 4,000 | 3,700 | 2,900 | 2,900 | |||||
| Ta | 3,500 | 3,300 | 2,900 | 2,500 | 3,450 | 2,900 | 4,250 | 2,300 | 2,300 | 2,200 | 3,500 | ||
| Ti | 2,300 | 2,300 | 2,300 | 1,700 | 1,900 | 2,300 | |||||||
| Ni | 2,300 | 2,300 | 2,300 | 1,700 | 2,300 | 2,200 | 2,300 | ||||||
| Fe | 2,200 | 2,200 | 2,200 | 1,900 | 2,200 | 2,200 | 2,000 | ||||||
| C | 2,700 | 2,700 | 3,200 | 2,500 | 2,500 | 3,600 | 2,900 | 3,500 | 2,300 | 2,300 | 2,000 | 4,000 |