A Knudsen effusion technique with mass‐spectral analysis of evaporated products has been applied for determination of nature and amounts of substances that evolve from mould powders (MP) into the environment in the process of continuous casting of steel. The experiments revealed that the main volatile fluorides that contaminate air in the working zone of a continuous caster are NaF, KF, SiF4, AlF3, NaAlF4, CaF2. A high proportion of these volatile fluorides as well as components of MP such as CaF2 and Na3AlF6 with water produces HF. Concentrations of different fluorine compounds in the working grounds of a caster depend on chemical and ingredient compositions of MP, basicity and moisture content, technology of MP manufacturing, humidity of atmosphere.
the lower part of the zircon--graphite nozzle often breaks off because the breaking force is evidently greater than the tensile strength of the nozzle. This phenomenon can be prevented by aligning the zircon--graphite and quartz nozzles correctly during their installation.It was suggested that the strength of the zircorr-graphite nozzles might be increased by replacing some of the pulverized zircon in the mix with refractory clay DNI. Tests were .......... out with composition containing 5, i0, 20, and 40% of clay.An analysis of the specimens after the heat treatment showed that their cold-crushing and tensile strength decrease in proportion with the amount of added clay; the thermal-shock resistance, refractoriness under a load, and slag resistance also decrease.
CONCLUSIONSA technology for the production of zircon-graphite nozzles was developed and introduced. This technology is simpler than that used at the Krasnoarmeisk Dinas Plant. Zircon-graphite nozzles are stronger than zircon nozzles and less prone to encrustation during the casting of high-aluminum steel.
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