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This work aims to analyze the effect of mechanical activation on structural disordering (amorphization) in an alumina-silica ceramics system and formation of mullite most notably at a lower temperature using X-ray diffraction (XRD). Also, an objective of this work is to focus on a low-temperature fabrication route for the production of mullite powders.

A batch composition of kaolin, alumina and silica was manually pre-milled and then mechanically activated in a ball mill for 30 and 60 min. The activated samples were sintered at 1,150°C for a soaking period of 2 h. Mullite formation was characterized by XRD and scanning electron microscopy (SEM).

It was determined that the mechanical activation increased the quantity of the mullite phase. SEM results revealed that short milling times only helped in mixing of the precursor powders and caused partial agglomeration, while longer milling times, however, resulted in greater agglomeration.

It is noted that, a manual pre-milling of approximately 20 min and a ball milling approach of 60 min milling time can be suggested as the optimum milling time for the temperature decrease succeeded for the production of mullite from the specific stoichiometric batch formed.

There is still a real demand in the glass industry for fire bricks for crucibles, e.g. for the production of glass with low iron content, or special glasses. The results mentioned herein should not be taken to mean that in future, fire bricks used for glass production should, in all cases, be replaced by ZAC bricks. For high quality production, however, the use of the relatively expensive type is justified.

In this paper, the chemical reactions between the white rice hull ashes and the aluminum powders, obtained from milled beverage cans, were investigated under different temperature and atmosphere conditions. Controlling the temperature and the atmosphere conditions resulted in different composites. XRD and SEM characterization technologies were employed to examine the features of the produced composites. Without the presence of oxygen, the white rice hull ashes and the aluminum powders reacted to form the ceramic-metal composites with a networked structure. After raising the temperature from 720°C to 1450°C, the Al₂O₃ in the composites tends to turn into crystal structure from the original amorphous form. On the other hand, with an O₂ atmosphere, the white ash and aluminum system would evolve to mullite or mullite/alumina composites, depending on the ratio of silicon and aluminum in the initial system. This study extended the application of the rice hull, which is a major agricultural waste, and may pave a new route to deal with the agricultural problem as well provide a new industry opportunity.

The purpose of this paper is to study the rapid prototyping of porcelain products by using layer‐wise slurry deposition (LSD), in order to reduce the time to market of new or customized porcelain products or artworks.

The properties such as phase composition, microstructure, shrinkage, density, and mechanical strength, of laser sintered (LS) and biscuit fired (BF) samples, before and after post sintering in a furnace, were studied and compared with each other.

The laser sintered sample was comparable with the biscuit fired sample in porosity, but had just half the mechanical strength of the latter due to the layer‐wise fabrication process. The feasibility of rapid prototyping of porcelain products was validated by the successful fabrication of some porcelain samples, which showed that the relatively low mechanical strength of the laser sintered sample was still high enough for the following handling processes, such as surface glazing and glost firing.

The paper demonstrates the possibility of rapid prototyping of porcelain components and the models produced by using LSD process.

Zirconia ceramics exhibit high strength and fracture toughness. The purpose of this paper is to research a possibility of crack healing in zirconia ceramics.

ZrO₂/SiC composite ceramics are sintered and subjected to three‐point bending. A surface crack of 100 μm in diameter is formed on each specimen. The cracks are healed and the specimens are tested under bending.

The paper finds that ZrO₂/SiC composite ceramic material had a high crack‐healing ability at a considerably low temperature. For example, a crack of 100 μm in diameter is healed even at 600°C.

The paper provides a low temperature healing and a new mechanism of crack healing.

The paper shows the healing temperature and the minimum time required to heal showed a good proportional relation on the Arrhenius plot at temperatures of 600‐800°C. Moreover, the crack healing is caused by SiO₂ cristobalite produced during the healing.

The purpose of this paper is to prevent their recession caused through chemical reaction with high-temperature water vapor, SiC-fiber/SiC-matrix ceramic-matrix composite (CMC) components used in gas-turbine engines are commonly protected with so-called environmental barrier coatings (EBCs). EBCs typically consist of three layers: a top thermal and mechanical protection coat; an intermediate layer which provides environmental protection; and a bond coat which assures good EBC/CMC adhesion. The materials used in different layers and their thicknesses are selected in such a way that the coating performance is optimized for the gas-turbine component in question.

Gas-turbine engines, while in service, often tend to ingest various foreign objects of different sizes. Such objects, entrained within the gas flow, can be accelerated to velocities as high as 600 m/s and, on impact, cause substantial damage to the EBC and SiC/SiC CMC substrate, compromising the component integrity and service life. The problem of foreign object damage (FOD) is addressed in the present work computationally using a series of transient non-linear dynamics finite-element analyses. Before such analyses could be conducted, a major effort had to be invested toward developing, parameterizing and validating the constitutive models for all attendant materials.

The computed FOD results are compared with their experimental counterparts in order to validate the numerical methodology employed.

To the authors’ knowledge, the present work is the first reported study dealing with the computational analysis of the FOD sustained by CMCs protected with EBCs.

The purpose of this paper is to study and analyze the effects of fly ash (FA) as a mineral admixture on compressive strength (CS), carbonation resistance and corrosion resistance of reinforced concrete (RC). In addition, the utilization of inexpensive and abundantly available FA as a cement replacement in concrete has several benefits including reduced OPC usage and elimination of the FA disposal problem.

Reinforcement corrosion and carbonation significantly affect the strength and durability of the RC structures. Also, the utilization of FA as green corrosion inhibitors, which are nontoxic and environmentally friendly alternatives. This review discusses the effects of FA on the mechanical characteristics of concrete. Also, this review analyzes the impact of FA as a partial replacement of cement in concrete and its effect on the depth of carbonation in concrete elements and the corrosion rate of embedded steel as well as the chemical composition and microstructure (X-ray diffraction analysis and scanning electron microscopy) of FA concrete were also reviewed.

This review provides a clear analysis of the available study, providing a thorough overview of the current state of knowledge on this topic. Regarding concrete CS, the findings indicate that the incorporation of FA often leads to a loss in early-age strength. However, as the curing period increased, the strength of fly ash concrete (FAC) increased with or even surpassed that of conventional concrete. Analysis of the accelerated carbonation test revealed that incorporating FA into the concrete mix led to a shallower carbonation depth and slower diffusion of carbon dioxide (CO₂) into the concrete. Furthermore, the half-cell potential test shows that the inclusion of FA increases the durability of RC by slowing the rate of steel-reinforcement corrosion.

This systematic review analyzes a wide range of existing studies on the topic, providing a comprehensive overview of the research conducted so far. This review intends to critically assess the enhancements in mechanical and durability attributes (such as CS, carbonation and corrosion resistance) of FAC and FA-RC. This systematic review has practical implications for the construction and engineering industries. This can support engineers and designers in making informed decisions regarding the use of FA in concrete mixtures, considering both its benefits and potential drawbacks.

To begin this paper provocatively I will put forward the opinion that information work in any field is always largely empirical; information work in a technology cannot be anything else but empirical. It is impossible to organize an information service for a technology until the broad outline of the technology itself has been understood and assimilated. This being so, it is only possible to speak to any purpose on information work in a technology if, at each stage, some specific technology is used as a framework of reference; the only such framework known to the present author is that provided by the ceramic industry. It has been objected that the ceramic industry cannot provide a broad enough framework to give interest to an audience drawn from other industries; I hope to be able to show that this objection is not valid. To do so, the term ‘ceramics’ must first be defined.

This paper aims to explore the preparation and tribological performance of MoS₂ nanoparticles supported on fly ash (FA) microparticles.

FA was activated by NaOH, oleic acid and HCl to obtain three modified FA samples. Nano-MoS₂ was deposited on them to form MoS₂/FA additives for poly-α-olefin (PAO) modification. Tribological tests were conducted on a reciprocating rig through the ball-on-disk friction manner. Using X-ray diffraction, scanning electron microscope, energy dispersive spectrometer, Raman spectrometer and element analyzers, the products and their lubrication mechanisms were characterized.

At 1.5 Wt.%, nano-MoS₂ and MoS2/FA could remarkably improve the tribological properties of PAO. The nano-MoS₂ deposited on the HCl-activated FA presented better lubrication performance than nano-MoS₂. It could reduce friction and wear by approximately 27% and approximately 66%, respectively. The lubrication of MoS₂/FA can be attributed to the formation of MoS₂ and carbon containing lubricating film.

FA was applied as a supporter to prepare MoS₂/FA lubricants. The reuse of FA, a solid waste, is important for environmental protection. Moreover, MoS₂/FA is more economical than nano-MoS₂ as a lubricant, because it contains approximately 71% of low-cost FA.

The paper aims to study the friction behaviour of alumina and zirconia against steel DIN‐Ck45K under water lubricated conditions.

The tests were performed with a contact stress of 3.5 MPa and a constant sliding velocity of 0.5 m/s for 5.35 km of sliding distance, using a pin‐on‐disk tribometer.

The friction coefficient and the energy dissipated in the contact were considered in this comparative study. The zirconia ceramic present less friction coefficient and contact temperature than alumina ceramic. The zirconia present about 70 per cent of the energy dissipated against when compared with the alumina. Abrasive scars of the surface ploughing were observed on every wear track for two pairs in contact.

This research used only one test condition.

The paper describes the tribological conditions used and a new methodology based on the energy dissipated in the contact is proposed.