The effect of the raw materials and mixing ratio on the heat transfer and structure of mould slag was studied in the present paper. Three groups of mould slag with identical chemical composition were designed by various raw materials and mixing ratio. The result indicates that the raw material has minor effect on viscosity, melting point and crystalline phase of the mould slag; whereas, it affects the formation and size of crystal. The wollastonite in slag has higher crystallization capacity; therefore, it promotes the formation of thicker solid slag film with higher porosities and consequently prevents the strong heat flux through the slag film. Compared with wollastonite, prefused material in the slag has capability to restrain the crystallization process; hence, the thinner solid slag film with uniform size and finer grain is formed. The experiment proves that prefused mould powder has good performance on heat transfer.

As one of the most important factors on product surface quality and casting practice, the heat transfer across the interfacial layers in continuous cast mould is greatly affected by the formation of mould slag film between the solidifying shell and the mould. So far, many methods have been presented to measure the heat transfer of mould slag; however, few of them could be easily applied to represent the real heat transfer across the mould interfacial gap. An apparatus used for mould slag film heat transfer measurement is presented in the current paper. The apparatus is used to simulate the heat transfer across the mould slag film. According to the measurement, four parameters are selected as a standard to characterize the heat transfer of the mould slag. The parameters include maximum heat flux (liquid slag), characteristic time, heat flux at meniscus, and average heat flux. Two measurements on different mould slags verify that: 1) the standard could represent the difference in heat transfer between medium carbon steel and low carbon steel mould slag; 2) the average heat flux is a key factor to indicate the overall heat transfer in casting mould; 3) the formed solid slag film in experiment is identical to the real mould, including the morphology, composition, grain size, and thickness. The experiment simulation offers an effective approach to study the formation and evaluation of slag film inside the mould.

Applying image analysis to fabric quality evaluation is suggested as a substitute for human inspection of fabric surfaces. A fabric image is captured on an image scanner, and from it, the coefficient of variation and power spectra of yarn interval are calculated as indices of irregularity in the yarn arrangement. However, neither shows a significant relationship with the results of human evaluations. As another approach to the irregularity of fabric surfaces, the power spectral peak width of the intensity data is computed. The peak width, containing surface irregularity information, shows it is related to fabric quality. The study also shows that the peak width changes with the back beam height.