Bath furnaces

A variety of heating equipment is used in a laboratory, namely, gas burners, plates, baths, furnaces, drying cabinets, etc. 

Direct Processes, i.e. Extraction of Metallic Antimony direct from the Ore.—(a) Bath Furnaces.—T. C. Sanderson has patented a process for the smelting of antimony sulphide in a bath of ferrous... 

When a piece of cold metal is suddenly immersed in molten salt, lead, zinc, or other molten metal, the molten liquid freezes on the surface of the cold metal, and heat is transferred by conduction only. After a very short time, the solid jacket, or frozen layer, remelts. From that time on, heat is transferred by conduction and convection. For that reason, discussion is postponed to the next section. Experimental determination of the heat transfer coefficient for heating metal solids in liquids is difficult, so practice is to record time in bath for good results as a function of thickness of strip or wire, as shown in section 4.7.1. on liquid bath furnaces. 

CONTINUOUS LIQUID HEATING FURNACES 4.7.1. Continuous Liquid Bath Furnaces... 

In most industrial heat-processing furnaces, it is desirable to have the entire furnace chamber at a positive pressure with an automatic furnace control system having a setpoint of 0.02 in. wc (0.5 mm) at the elevation of the lowest part of the load(s) or better yet, at an elevation just below the lowest leak. To keep out tramp air inleakage, raise the furnace pressure enough to drive the neutral pressure plane below the furnace bottom, in a liquid bath furnace, below the liquid surface level. 

Fig. 1 shows the geometric dimensions of the specimen. The heat treatment conditions of the specimen is 830°C(vacuum) holding 15 minutes and 25 minutes for austenitisation, and then make it in the salt bath furnace immediately for tempering which the salt bath conditions were placed on each constant temperature of 290 °C, 310 C and 330 C for 30 minutes, 60 minutes and 120 minutes, then quench in the water. Each austempering conditions are coded by the salt bath conditions, such as 290°C-30m. 

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