There are many. The Dayton Process BV is the only FIC process that uses Teflon as a source of the fluoride ion. This is much safer to handle than the gaseous hydrogen fluoride used in other systems. Gaseous systems must usually be installed in enclosed rooms to minimize the risk of an HF leak and require more preventive maintenance. Unlike gaseous processes, the Dayton Process BV doesn’t require pulsing of gas to create effective cleaning so it is much simpler to operate and cycle times are shorter. Furthermore, the Dayton Process BV involves very dry chemical reactions so there is little risk of intergranular attack. Gaseous processes involve reactions that create moisture thereby increasing the risk of intergranular attack.
Hot zone life depends on several factors including type of construction, type of use (ie. heat treating versus brazing), cleanliness of the load being processed and maintenance. In general heat treating applications, a properly maintained hot zone should last 5 to 7 years. Once worn out, it can sometimes be rebuilt rather than replaced. VAC AERO can re-build and replace hot zones for any brand of vacuum furnace. We also offer preventive maintenance programs to extend the life of your furnace.
HVOF stands for high velocity oxygen fuelled and is a type of thermal spray process used to apply very dense coatings in a wide variety of materials. Coatings applied by HVOF usually have better mechanical properties than those applied by air plasma spray. The HVOF process is now widely used to apply WC-Co coatings as an environmentally friendly alternative to chromium plating on high strength steel aircraft structural components.
There are a lot of factors to consider in this decision and every situation will be unique. A vacuum furnace is a large capital investment and there are other costs associated with setting up in-house that must be taken into account (see our Articles page). You also gain improved turn-around-time and important intangibles such as increased control over a very critical process. Because we offer both heat treating services and equipment, VAC AERO can assist you in conducting an analysis to determine the best-value business solution for your organization.
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Yes, it can, but there are some issues to consider. A standard vacuum furnace heats its load most effectively at temperatures above 1200°F (650°C), the start of the “red heat” range when radiant heating becomes most efficient. Below 1200°F (650°C), temperature uniformity within the furnace becomes a concern. Tempering operations for many alloys take place at temperatures well below the red heat range. Depending on load factors such as mass, configuration and section thickness portions of the load may not get properly tempered. Vacuum furnaces can be built with a convection heating capability to improve uniformity at lower temperatures, but this still may not be sufficient to meet some of the more stringent temperature uniformity requirements.