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The purpose of this paper is to investigate epoxysilane‐modified silica sols as surfactant‐free inorganic pigments dispersants and as co‐binders/reinforcing agents for silicate paints.

The performance of epoxysilane‐modified silica sols as dispersants for titania was studied using a polyacrylate‐based dispersant as reference. Furthermore, the effect of the addition of silica sols, with or without silane modification, to potassium silicate on binder properties was investigated.

Significant improvements were obtained in stability towards settling in water‐based titania pigments pastes and in light‐scattering efficiency (as much as 50 per cent) for the optimal size of the silica particle of 5 nm. The number of silane molecules per nm² silica particle surface must exceed a critical value of at least 1 molecule of epoxysilane per nm² particle surface. Additionally, improved stability towards gelling, water resistance and film‐forming properties of sol‐silicate binder mixes were achieved for epoxysilane‐modified silica sols.

Only epoxysilane‐modified silica sols were studied in this report. Titania pigment was examined but other important pigments (e.g. iron oxides) remain to be studied. In addition, only sol‐silicate mixes were investigated and not fully formulated silicate paints.

A method that produces stable, high‐performing, surfactant‐free inorganic pigments pastes. Furthermore, stable, high‐ratio, sol‐silicate binders can be obtained with improved water resistance and film properties for use in silicate paints.

The present method provides an easy route to obtain stable surfactant‐free inorganic pigments pastes, as well as makes stable, high‐ratio, sol‐silicate mixes/paints.

The selective laser sintering (SLS) process is used to prepare test bars from Al₂O₃/polymer binder powders. Finds that binder‐coated A1₂O₃ particles formed bars that were approximately twice as strong as could be formed from mixtures of alumina and polymer binder at the same binder level and processing conditions. In mixed systems, bar strengths increased nearly in proportion to increases in polymer binder content over the 20‐40 per cent volume binder range. Parts made in any particular laser scanning mode showed optimum values for strength and density as the laser energy density was systematically increased from 2‐8cal/cm². Suggests that optima result from the counteracting influences of energy density on binder fusion and thermal degradation. The optimum energy density is mode or geometry sensitive and shifts to lower values as the laser scanning vector is reduced. Concludes that this behaviour is probably the result of the lower heat losses. Equivalently better utilization of laser energy is associated with the shorter scan vectors. Some of the SLS fabricated bars were infiltrated with colloidal alumina, fired to remove the binder, and sintered at 1,600°C to achieve alumina bars with 50 per cent relative densities, interconnected porosity, and strengths between 2 and 8MPa.

A new rapid tooling technique named Rapid Pattern Based Powder Sintering (RPBPS) has been developed. It comprises the steps of first building a pattern made of polymer materials using a rapid prototyping machine based on a 3‐D CAD model. The pattern is positioned on a substrate in a box or frame, then a mixture of metal (ceramic or polymer) powder and binder is cast around the pattern. Next, there is a step of removing the pattern and separating the substrate to obtain a green compact that has the desired cavity. Then the green compact will be sintered and/or infiltrated to form a tool or part. The new technique has the advantages of using a variety of materials, rapidity, making complex geometry parts and low cost, compared with several existing rapid tooling techniques. Many key technical problems in RPBPS are related to the binder. In order to select a suitable binder, the heat deformation resistance and heat stabilization of some polymer materials are discussed in depth.

Thixotropy can be regarded as the loss of viscosity in a paint or other material that is brought about by mechanical agitation, and where the viscosity continues to decrease provided that this disturbance is continued for a period of time. Conversely, when the mechanical force is removed, the material then increases in viscosity and this recovery toward the initial structure continues to take place over a period of time. Sometimes the time dependency of the viscosity is vanishingly small so that the material is then properly referred to as pseudoplastic. In most of the literature, however, it is not usually possible to differentiate between thixotropy and true pseudoplasticity and therefore both kinds of structure are included in this review as they each are destroyed by mechanical agitation and recover when this is discontinued.

The purpose of this paper is to assess a new powder metallurgy process to make alumina parts through indirect selective laser sintering (SLS). Density measurements, some geometrical assessments and scanning electron microscopy (SEM) microstructural analyses are performed after each stage of the process, allowing an objective overview to be provided of the challenges and possibilities for the processing of high density technical ceramic parts through SLS of ball milled alumina/polyamide powder agglomerates.

The powder production by ball milling, SLS, cold isostatic pressing (CIP) or quasi isostatic pressing (QIP), debinding and sintering (FS) stages of the powder metallurgy process were sequentially investigated.

Alumina parts with a density up to 94.1 per cent could be produced by a powder metallurgy process containing an SLS step. Microstructural investigation of the sintered samples reveals an alumina matrix with a grain size of ∼5 μm and two different kinds of pore morphologies, i.e. long elongated pores, which stem from the intergranular spacings during SLS, and intermediate pores, which likely originate from larger polyamide agglomerates in the ball milled powder. Also, QIPing at elevated temperatures is found to be a promising alternative for CIPing at room temperature to increase the final part density.

Cracks, long elongated pores and intermediate pores remained in the sintered parts. Homogenizing the microstructure of the parts through optimizing the composite starting powder, the deposition during SLS, the SLS parameters and QIPing parameters is essential to overcome these limitations.

Homogenizing the starting powder mixture and the microstructure of the SLS material is the key issue for producing ceramic parts through indirect SLS.

Indirect SLS of ceramics has hardly been reported and the combined use of SLS and QIPing is innovative in the field of indirect SLS of ceramics.

The various types and application of bonded coatings are described, and their ability to reduce friction and wear. The composition and nature of the active ingredients are also covered, together with brief details of manufacturing processes. Examples are given of typical current application areas, although the potential of these types of coatings is such that the number of new applications is escalating rapidly.

The spectrally selective solar absorption paint is prepared from spinel-based mixed metal oxides with inorganic binder as a key component. Inorganic binder (furnace cement) is blended with mixed metal oxide pigment during synthesis. High temperature stability upto 1,100ºC is achieved by the use of this modified coating system. The purpose of this paper is to work on solar selective coating synthesis, and application of a coating as a water-borne paint is the additive key feature that helps in reduction of solvent use.

The paint was formulated using water-based system, and the main component of colorant was made by mixed metal oxide–based spinel pigment and highly temperature stable inorganic binder.

The paint formed shows excellent absorptive power with low emittance even at high temperature. Optical and thermal properties were determined along with adhesion, abrasion and other properties. The solar absorptance for these samples were as = 0.93–0.95 with corresponding thermal emittance of eT = 0.096 (at room temperature) and 0.2–0.22 (at elevated temperature 100°C).

The paint formed shows excellent absorptive power with low emittance even at high temperature. The paint can be applied in solar absorptive tower system. The obtained results indicated excellent thermal stability of prepared paint coatings. As inorganic binder was used, the paint has reduction in solvent use, and being water as a base, it is environment friendly, easy to apply and durable at high temperatures, as the binder itself is stable up to 1,500ºC.

A mixed metal oxide-based spinel ceramic pigment has been successfully synthesized incorporating inorganic, high-temperature stable furnace cement as an inbuilt binder. Step by step synthesis was done for the spinel and cement mix formulations.

The pigment mix was synthesized by a solid-solid method where the inorganic binder was incorporated in the mix. The results suggested that CoCuMn-based spinel ceramic pigment with cement mix could be obtained at an annealing temperature of 1,100ºC for 1 h and the size, morphology and crystallinity of spinel mix were greatly influenced by the calcination temperature.

The pigment mix synthesized was applied as a coating to different substrates such as aluminum, glass and Mild steel. The results revealed that spectral selectivity of TSSS paint coatings based on the CoMnCu spinel ceramic mix was much better than that of solvent-based coatings for high-temperature applications. The presence of cement as an inorganic binder makes the functioning and application of paint easy as it becomes that of a waterborne type.

Ease of application, stability at high temperatures, best absorptivity at the solar selective spectrum and excellent adhesion properties for the selected surface are the key features of the designed pigment system. The applied pigment mix was studied as a coating to get the results for solar selective system.

The purpose of this paper is to analyze the current state of the art manufacturing techniques using sand molds for the casting industry by the means of additive manufacturing (AM). In particular, this review will cover two families of 3D printing in regards to sand mold fabrication.

This paper will discuss the sand casting manufacturing processes of AM by binder jetting (3D printing) and selective laser sintering. Scientific articles, patents and case studies are analyzed. Topics ranging from the technology types to the economic implications are covered.

The review investigates new factors and methods for mold design, looking at mechanical properties and cost analysis as influenced by material selection, thermal characteristics, topological optimization and manufacturing procedure. Findings in this study suggest that this topic lacks vigorous scientific research and that the case studies by manufacturers thus far are not useful.

As demonstrated by the limited data from previous published studies, a more comprehensive and conclusive analysis is needed due to the lack of interest and resources regarding the AM of sand molds.

This study is a useful tool for any researchers with an interest in the field of AM of sand molds.

Key perspectives are proposed.

This review highlights current gaps in this field. The review goes beyond the scientific articles by curating patents and professional case studies.