Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
Of the Members, By the Members, For the Members!
VacuumFurnaces.com is a Q&A community where vacuum furnace product and service suppliers connect with commercial and captive heat treaters to share their practical skills and know-how and to establish valuable relationships around niche topics of expertise with vacuum furnace end-users in operations, production, training, maintenance, marketing, sales, and engineering.
CFC, Graphite, or Moly, which is the best choice for vacuum ovens?
Hot zones are the hearth of every vacuum furnace. When purchasing a new furnace, you might face with the Hamletic doubt about hot zones: graphite-based or all-metal design hot zone? That’s the question! The graphite wafer is an excellent material. It allows operation at very high temperatures (up toRead more
Hot zones are the hearth of every vacuum furnace. When purchasing a new furnace, you might face with the Hamletic doubt about hot zones: graphite-based or all-metal design hot zone? That’s the question!
The graphite wafer is an excellent material. It allows operation at very high temperatures (up to 3000°C based on the vacuum level), has low density, reduced weight and modest thermal capacity. It creates the ideal black body conditions (emissivity about 1) inside the heating chamber for obtaining high uniformity.
All-metal hot zones are used in high demand industries where sensitive materials are processed, such as aerospace, electronics and medical. There are heat treatments that require a particularly clean environment or extreme vacuum levels. There may be different reasons: in some cases the chamber’s graphite could interfere with the process, resulting in unwanted carburation of the pieces treated. In other cases, the load could be particularly sensitive to the presence of residues in the oxygen or hydrogen atmosphere (which could lead to embrittlement of the pieces), and so graphite wafer degassing during the cycle could be damaging. In these circumstances, the user should opt for all-metal heating chambers (shields and resistor).
If you want more information on this topic and a detailed analysis of the differences, take a look at the following 2 articles:
See lessVacuum furnace hot zone: graphite vs all-metal design [1/2]
Vacuum furnace hot zone: graphite vs all-metal design [2/2]
Why use partial pressure in a vacuum furnace?
Partial pressure can be used to assist in removing impurities and heat distribution during the heating process.
Partial pressure can be used to assist in removing impurities and heat distribution during the heating process.
See lessWhere is it required to do hydrogen bakeout?
Hydrogen bakeout is commonly used for materials or processes when hydrogen induced cracking is a concern. Heating the material to a temperature high enough and long enough to allow the trapped hydrogen to escape from the areas where it is trapped in the material. This is a common process for post weRead more
Hydrogen bakeout is commonly used for materials or processes when hydrogen induced cracking is a concern. Heating the material to a temperature high enough and long enough to allow the trapped hydrogen to escape from the areas where it is trapped in the material.
This is a common process for post welding of chrome moly steels that do not use low hydrogen welding processes or electrodes and heavy weldments.
See lessWhat temperature is vacuum brazing performed at?
Technically brazing is performed above 840F. Vacuum furnace brazing temperatures are determined by the braze filler metal being used and the base metals involved. You should refer to the appropriate material specification for your industry for the applicable variables.
Technically brazing is performed above 840F. Vacuum furnace brazing temperatures are determined by the braze filler metal being used and the base metals involved. You should refer to the appropriate material specification for your industry for the applicable variables.
See lessWhat is the difference between freeze protection and burst protection in a water cooling system?
Freeze Protection requires a glycol concentration level sufficient to prevent the formation of ice crystals at the lowest temperature experienced by the fluid. Freeze protection is imperative when the system requires pumping. Slush is formed when you get colder than its freeze protection rating. BurRead more
Freeze Protection requires a glycol concentration level sufficient to prevent the formation of ice crystals at the lowest temperature experienced by the fluid. Freeze protection is imperative when the system requires pumping. Slush is formed when you get colder than its freeze protection rating.
Burst Protection only requires a glycol concentration high enough (generally 30% by volume or more) to prevent bursting and other mechanical damage from freezing, but not necessarily high enough to keep the fluid pumpable. Burst protection requires less glycol than freeze protection and is suitable for chilled water systems that are dormant in the winter. As the temperature drops below the freezing point of the fluid in a system with burst protection, ice crystals begin to form, and the solution becomes a slush. The fluid expands as ice is formed. This mixture may or may not be pumpable, but it is fluid enough so that the excess volume flows into an expansion tank without damage to the system. As the temperature drops further and all the water freezes, the glycol will begin to freeze and contract.
Source:Â Dry Coolers
See less