Ceramics

During the Early Byzantine period, ceramic vessels evolved from Roman pottery; red-slip tableware produced by Asia Minor and North African workshops dominated the market. Christian motifs enriched the decorative repertoire. From the seventh century onward, glazing signaled a major change in the appearance of vessels during the Middle and Late Byzantine periods. Glazed White Ware from Constantinople monopolized the tableware market until the eleventh century. From this time onward a light-colored slip layer on red fabric ensured a surface suitable for decoration and allowed for the development of sgraffito decoration, the Byzantine pottery decorative technique par excellence. It also made the production of glazed decorated ceramics possible in parts of the empire without white clay. During the Late Byzantine period, decentralization of pottery workshops allowed the development of local characteristics.

Study on wall-slip effect of magnetorheological fluid and its influencing factors

The wall-slip effect is observed in areas with magnetorheological fluids (MRFs). A slip layer is formed, which reduces the friction between the solid particles and working surface that causes relative movement of the particles. This leads to errors in the measurement of rheological parameters and an inaccurate braking torque model. Thus, here, a rheometer with a sandpaper on the rotor is used to change the working surface roughness to analyze the wall-slip effect of the MRFs. Based on the experimental results, the influence patterns of wall-slip effect on fluid viscosity and yield stress are obtained. Furthermore, a MRF model is established that considers wall-slip effect, which is different from the conventional models. The model is employed to establish a magnetorheological (MR) braking torque model. To verify the braking torque model, a prototype was manufactured, and its mechanical properties were tested. When compared with a smooth rotor, the braking torque of MR brakes with rectangular grooves is increased. This confirms the existence of the wall-slip effect and shows that the wall-slip effect of MRF can be effectively suppressed by incorporating grooves on the rotor surface.

Investigation of the Influence of Technological Regimes of High-Temperature Firing on the Structure and Properties of Silicate-Enamel Coatings for Carbon Steels

The silicate-enamel coating becomes the actual coating as a result of firing, which is a process of heating steel products coated with a “biscuit” dried slip layer, until completely melted, and a continuous coating is obtained on a metal substrate. With the constantly increasing requirements for the technical and operational properties of enameled products in the production of steel pipelines, it is advisable to use single-layer enameling, which saves raw materials and energy, due to the reduction in the number of layers and firing cycles of products. Its use for large-sized products, such as pipelines, eliminates their warping that occurs during repeated firing. In addition, the use of single-layer coatings makes it possible to obtain a better surface of products, since with a decrease in the resulting coating thickness it becomes more elastic and impact-resistant. All of the above is predetermined both by the structure of the glass coating itself and the generally formed steel - enamel composition. Therefore, knowledge of the structure, as well as of the physicochemical processes that occur during the firing of the enameled product, is necessary to solve technological issues successfully.

Slip layer estimation of shallow landslides on Aso volcanic mountains in Japan based on tephra layer-physical properties of soil

Shallow landslides occur frequently on the Aso volcanic mountains. The soil material on the Aso volcanic mountains consists of tephra layers formed by volcanic activities. This study is aimed at determining the physical properties of soil that correlate with the slip surface of a shallow landslide on the volcanic mountain area. Tephra layers consist of kuroboku and scoria layers and the differences between these layers have been determined using the physical properties of soil methods. This study showed that the plasticity index and the fine fraction content can be used for estimating the slip layer in the Aso volcanic area.

Recording microindentation and adhesion tests to analyse the depth-dependent mechanical and adhesive properties of multilayer polymer films as shown for gelatine-coated polyethylene terephthalate and polyethylene films

Further developed methods based on an indenter penetration into a material allow generalised quantitative statements on the composition, the depth-dependent mechanical properties and the delamination behaviour of multilayer polymer films, which is demonstrated on gelatine-coated polyethylene terephthalate and polyethylene films. These highly sensitive polymer testing methods, include the recording microindentation test and the recording adhesion test, describe the material behaviour multi-parametrically and are fast (raw data acquisition within several minutes) and relatively simple, requiring a minimum 1 gram sample depending on the film thickness. Based on the Vickers hardness under load approach, the hardness–depth diagrams calculated from the recording microindentation test provide information about the structure, the thickness and the coating hardness and the substrates. The tangential load vs. tangential path length diagrams from recording adhesion test can detect different scratch processes such as continuous scratching or non-continuous stick-slip layer delamination. Furthermore, they form the basis to quantitatively analyze adhesion, i.e. to determine the critical tangential load and the critical tangential delamination work. Both are highly dependent on the substrate type and treatment.