Crucible cements

Alundum is used for highly refractory bricks (m.p. 2000-2100 C), crucibles, ref ractory cement and muffles also for small laboratory apparatus used at high temperatures (combustion tubes, pyrometer tubes, etc.). 

If there is one, record the unknown number of your cement material. Using the analytical balance, weigh approximately 1.0 g of the cement (do not dry first) into the crucible, transferring with a spatula. If the balance has a tare feature, you may use it, but make sure you have the weight of the crucible with lid recorded. 

Sources. From manufacture of refractory crucibles, fire bricks, magnesia cements, boiler scale compounds... 

Most fusions use lithium tetraborate (Li2B407, m.p. 930°C), lithium metaborate (LiB02, m.p. 845°C), or a mixture of the two. A nonwetting agent such as KT can be added to prevent the flux from sticking to the crucible. For example, 0.2 g of cement might be fused with 2 g of Li2B407 and 30 mg of KI. 

Huntsman Also called the Crucible process. A method for purifying blister steel, made by cementation, by melting it in a closed clay or graphite crucible and pouring the melt into a cast iron mold. Developed by B. Huntsman, a clockmaker, around 1740, initially in Doncaster and later in Sheffield, UK. The process was not patented but was operated in secrecy for some years. It was subsequently widely operated in the UK, Europe (where the combination of this with the cemen-... 

K,oH3[Y(SiW,039)2] was compacted into a round piece (diameter=10mm, high=3mm) under 12MPa. The permeable reagent was self-made [9]. The equipment was a crucible cementation furnace with the XMT-101 fine temperature controller. The DP temperature was 550°C and the DP time was 2h. The system was cooled down naturally. The conductivity measurement was performed on a conductivity measuring system and the permeated rare-earth was determined by ICP, and the structure of the sample was detected by IR, XRD spectrometer. 

The function of the clay is that of a bonding material, which makes possible the shaping of the crucible and the cementing together of the graphite flakes. At the same time, it covers the particles, and thus protects them from oxidation. In order to be most effective in regard to this point, it is necessary that the clay contract and become dense at as low a temperature as is consistent with the required refractoriness. 

JSE For "lead" pencils, refractory crucibles, < iove polish pigment lubricant, graphite cement for matches and ex-... 

Dead-burned As refractory brick for cement kilns, furnaces, crucibles, and equipment used in the manufacture of steel ... 

A lead cooling coil is wrapped aroimd the cemented area. Stopcock h may be used both as a vacuum connection and a gas inlet. A peephole/cemented onto g, permits observation of the material in the crucible. 

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