Elaboration of TiO2 Ultrafiltration Membrane Deposited on Moroccan Sahara Clay

In this work, the porous ceramic multilayer ultrafiltration membrane is developed. Macroporous support was formed by extrusion of ceramic paste derived from natural Moroccan Sahara Clay. The microporous interlayer was then performed by slip casting from zirconia commercial powders and finally the active ultrafiltration toplayer was obtained by solgel route using TiO2 sol. The performance of TiO2 ultrafiltration membrane was evaluated by pores diameter, thickness of the top layer, water flux, and molecular weight cut off (MWCO). The water permeability measured for this composite membrane is 9.051 l/(m2·h·bar), the thickness is around 900nm, the pore diameter is centered near 7nm and the MWCO was about 5000Da.

Modeling and Numerical Study of Ceramic Paste Extrusion

The extrusion processes of ceramic pastes, including 3D printing, are used for the production of high-value products. Ceramic paste extrusion is a complex process which depends on the paste rheological properties, die and extruder geometries, and operational parameters. Modeling and quantitative analysis of paste molding are important to design proper extrusion process for the production of high-value extrudates of desired strength, shape, and morphology. In this paper, the mathematical model of ram extrusion of ceramic materials is established, and the paste continuity and momentum equations for non-Newtonian fluid based on the modified Herschel-Bulkley viscous model were solved numerically. The effects of die geometry and paste feed rate on the distributions of paste velocity and pressure in the extruder and die were investigated numerically. As a result, the steeper radial profile of longitudinal velocity and higher value of longitudinal velocity were obtained in the narrow die. The pressure significantly increases in the die at a high feed rate, and the pressure profile is almost flat in the barrel. The rate of increase of the maximum pressure decreases with an increase of paste feed rate. The pressure steeply increases in the die of small diameter. The maximum pressure linearly increases with the ratio of die length to diameter.

Development of composite electrode materials based on nickel oxide for additive manufacturing of fuel cells

In this work, a new composition of a paste based on nanosized nickel oxide (NiO) for jet-based 3D printing has been developed and investigated. The optimal parameters of anode paste with necessary viscosity and NiO loading have been found for printing by using custom made laboratory 3D printer. Experiments have been carried out to print two-and three-dimensional test objects using the developed ceramic paste; printing modes have been investigated to fabricate objects of a given shape and size with laser sintering of the deposited layers. Experiments have been conducted for the selection of optimal temperature conditions for the post-processing of the printed samples.

Technology of Reconditioning with Hardening of Working Elements of Construction and Road Machines by Composite Coatings

The article gives the description of the developed technology of increasing wear resistance of working elements of national and foreign constructional and road machines by composite coatings, obtained on working elements cutting surfaces applying Carbo Vibro Arc Hardening method (CVAH). The technology includes the following basic operations: cleaning and fault detection of the working element, removal of the worn cutting element, compensating element production, its sharpening and welding, preparation of metal and ceramic paste for Carbo Vibro Arc Hardening method (CVAH) and its application, Carbo Vibro Arc Hardening method (CVAH) of the harden cutting surface of the working element. When hardening new working elements technological process operations connected with production and welding the compensating element is not performed. According to the carried out results the rational composition and component concentration of the paste that provides significant increase of working elements wear resistance.

A review on additive manufacturing of ceramic materials based on extrusion processes of clay pastes

This paper aims to present a state of the art of additive manufacturing (AM) of ceramic materials based on extrusion processes of clay pastes, reviewing the definitions and classifications of the AM field under current international standards. A general overview on the AM category ‘material extrusion’ is provided and the class ‘paste deposition modeling’ is proposed for those techniques based on the extrusion of pastes that are solidified by solvent vaporization, with the aim of distinguishing it from the class ‘fused deposition modeling’, which is applied to extruded polymers through temperature plasticization. Based on the survey of background information on 3D printing technology by ceramic paste extrusion, a classification and historization of the innovations in the development of this technology are proposed.

Classic Maya Interaction Networks and the Production and Consumption of Cotton Fiber and Textiles

Ethnohistorical accounts of tribute among the Yukatek Maya provide an impressive list of materials and products in circulation at the time of Spanish contact while also affording a glimpse of the interwoven layers of socioeconomic relationships underlying these acts of exchange, tribute, and taxation. This chapter compares the 16th-century Yukatekan configurations with patterns of production and distribution of Classic period decorated ceramics that also link prime cotton-producing regions to major centers of political power. The data intimate that cotton and cloth were crucial components of Classic period exchange networks underlying political power. The study employs a multidisciplinary approach combining investigations of artistic style, ceramic paste chemical analysis, epigraphy, and archaeology.