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This paper aims to study the effects of solid additives and compounding processes on the selective laser sintering (SLS) behavior of composite powders.

Composite powders were prepared from TrueForm™ acrylic‐styrene co‐polymer and SiO₂ powder. Dry mixing and melt extrusion were used as the blending processes to produce the composite powders. Some SiO₂ powder was ground and treated with silane coupling agent before blending to study the effects of particle size and surface treatment of the filler, respectively. The temperature of the powder bed was monitored using an infrared thermometer. The fusion behaviors of the powders were investigated in situ using an optical microscope and the sintered specimens were examined by scanning electron microscopy.

For a given volume fraction of the filler, reducing its particle size will hinder fusion between the polymer particles and weaken the sintered specimens. Surface treatment of the filler by silane coupling agent had little effect on the morphology of the sintered specimens; however, it slightly improved their strength. The blending method plays an important role in the sintering behavior of the composite powders. Although melt blending improved the polymer‐to‐polymer contact between the composite powder particles, the high‐resultant viscosity of the material adversely affected the densification of the powder bed, leading to a highly porous structure of the sintered specimens.

The sintering experiments were conducted in ambient conditions using a laser engraving machine instead of a commercial SLS machine with atmospheric control. The temperature gradient within the powder bed was expected to be higher than that in normal SLS processes.

The SLS behavior of a composite powder not only depends on its composition but also on the powder preparation method or powder morphology.

This paper provides some useful information for future development of composite powders for SLS applications.

A method for rapid prototyping based on electrophotographic powder deposition was investigated to study its potentials and to identify design and implementation challenges. This technique is referred to here as the electrophotographic rapid prototyping (ERP). In this technique, powder is printed layer‐by‐layer in the shape of the cross‐sections of the part using electrophotography a very widely used non‐impact printing method. Each layer of powder is consolidated by fusing before the next layer of powder is printed. A fully automated test bed was constructed that consists of a printing system, fusing/heating plate, build platform that has two‐degrees of freedom as well as software that drives the system.

A comparison of selective laser sintering (SLS) and selective laser cladding (SLC) methods is presented. Loose single‐component, Ni‐alloy powder was used in this study. The powder feeding system formed the flow of powder particles directed into the zone of laser spot. The particles were deposited directly onto a substrate or onto the top of a pedestal. The powders were treated with a CW‐ Nd:YAG laser (λ=1.06 μm). The beam was motionless relative to the powder bed. As a result, the samples of sintered or remelted powders were built up as the vertical rods. The geometrical characteristics, structure and mechanical properties of samples were investigated.

Recycling technology for printed wiring boards (PWBs) with mounted electronic components was studied for the purpose of disassembling the boards, recovering useful materials, and reusing these materials. An automatic removal method was developed for the electronic components on the basis of a combination of heating to above the solder melting temperature and applying impacting the shearing forces. Most of the electronic components were recovered undamaged and the solder was able to be recovered as particles. The solder remaining on the board was recovered by abrading the board surface and by using a heating‐impacting process. After these processes, the resin board (a cured epoxy resin board reinforced with glass fibre)was pulverised and separated into a copper‐rich powder (copper: 82 Wt%) and a glass fibre and resin mixture powder (glass fibre‐resin powder) by gravimetric and electrostatic methods. The recovered electronic components, solder and copper‐rich powder were used as valuable metal resources for refining. Moreover, the recovered glass fibre‐resin powder was found to be a useful filler for plastic products such as epoxy resin and ABS (acrylonitrile/butadiene/styrene copolymer) resin.

The use of bimodal powders has been shown to offer the possibility of dramatically improved surface finish in 3D printing. This work focused on individual lines, the primitive building block of 3D printed parts. It was observed that the fine component of bimodal ceramic powders, while uniformly distributed in the original powderbed, was preferentially found at the surface of the printed line, while the interior of the line was denuded of fines. Microscopic examination and approximate quantitative analysis supports the assertion that essentially all the fines have moved to the surface of the line. The mechanism for this rearrangement is not known, but is speculated to be related to the relative difficulty of wetting fine powders. The parameter space in which this phenomenon can be observed was examined in a preliminary manner.

The consolidation process and morphology evolution in ceramics-based additive manufacturing (AM) are still not well-understood. As a way to better understand the ceramic selective laser sintering (SLS), a dynamic three-dimensional computational model was developed to forecast thermal behavior of hydroxyapatite (HA) bioceramic.

AM has revolutionized automotive, biomedical and aerospace industries, among many others. AM provides design and geometric freedom, rapid product customization and manufacturing flexibility through its layer-by-layer technique. However, a very limited number of materials are printable because of rapid melting and solidification hysteresis. Melting-solidification dynamics in powder bed fusion are usually correlated with welding, often ignoring the intrinsic properties of the laser irradiation; unsurprisingly, the printable materials are mostly the well-known weldable materials.

The consolidation mechanism of HA was identified during its processing in a ceramic SLS device, then the effect of the laser energy density was studied to see how it affects the processing window. Premature sintering and sintering regimes were revealed and elaborated in detail. The full consolidation beyond sintering was also revealed along with its interaction to baseplate.

These findings provide important insight into the consolidation mechanism of HA ceramics, which will be the cornerstone for extending the range of materials in laser powder bed fusion of ceramics.

This paper aims to study the effects of plum powder and apple pomace powder additions on the quality properties of buffalo meat emulsion.

Buffalo meat emulsions were prepared using different levels (2%, 4% and 6%) of plum powder and apple pomace powder, respectively. The meat emulsions were analysed for the physico-chemical, sensory and textural properties of the meat emulsion.

The pH of meat emulsions decreased significantly (p < 0.05) with an increased level of plum powder and apple pomace powder. Water-holding capacity (43.1%–48.1%), emulsion stability (80.2%–92.2%) and cooking yield (85.4%–91.0%) were significantly (p < 0.05) higher in plum powder and apple pomace powder added than the water-holding capacity (42.1%), emulsion stability (79.7%) and cooking yield (85.0%) of control emulsion. The moisture content was decreased significantly (p < 0.05), and crude fibre content was increased significantly (p < 0.05) with the increase in plum powder and apple pomace powder additions in meat emulsions. The total phenolic content and colour values (a* and b*) were significantly higher in plum powder and apple pomace powder added to meat emulsions. The sensory scores of meat emulsions were affected by the addition of plum powder and apple pomace powder. The meat emulsion added with 6% plum powder and 6% apple pomace powder showed significantly lower values of sensory overall acceptability. The hardness of meat emulsions increased with the addition of plum powder and apple pomace powder.

The results indicated that meat emulsions with a good cooking yield, fibre content, sensory acceptability and textural properties can be prepared by using plum powder and apple pomace powder.

This study aims to investigate the effects of ball–material ratio on the properties of mixed powders and Cu-Bi self-lubricating alloy materials.

Cu-Bi mixed powder was ball milled at different ball–material ratios, and the preparation of Cu-Bi alloy materials was achieved through powder metallurgy technology. Scanning electron microscopy, X-ray diffraction and Raman spectroscopy were conducted to study the microstructure and phase composition of the mixed powder. The apparent density and flow characteristics of mixed powders were investigated using a Hall flowmeter. Tests on the crushing strength, impact toughness and tribological properties of self-lubricating alloy materials were conducted using a universal electronic testing machine, 300 J pendulum impact testing machine and M200 ring-block tribometer, respectively.

With the increase in ball–material ratio, the spherical copper matrix particles in the mixed powder became lamellar, the mechanical properties of the material gradually reduced, the friction coefficient of the material first decreased and then stabilized and the wear rate decreased initially and then increased. The increase in the ball–material ratio resulted in the fine network distribution of the Bi phase in the copper alloy matrix, which benefitted its enrichment on the worn surface for the formation a lubricating film and improvement of the material’s tribological performance. However, a large ball–material ratio can excessively weaken the mechanical properties of the material and reduce its wear resistance.

The effects of ball–material ratio on Cu-Bi mixed powder and material properties were clarified. This work provides a reference for the mechanical alloying process and its engineering applications.

Polymer laser powder bed fusion (PBF-LB/P) is an additive manufacturing technology that is sustainable due to the possibility of recycling the powder multiple times and allowing the fabrication of gears without the aid of support structures and subsequent assembly. However, there are constraints in the process that negatively affect its adoption compared to other additive technologies such as material extrusion to produce gears. This study aims to demonstrate that it is possible to overcome the problems due to the physics of the process to produce accurate mechanism.

Technological aspects such as orientation, wheel-shaft thicknesses and degree of powder recycling were examined. Furthermore, the evolving tooth profile was considered as a design parameter to provide a manufacturability map of gear-based mechanisms.

Results show that there are some differences in the functioning of the gear depending on the type of powder used, 100% virgin or 50% virgin and 50% recycled for five cycles. The application of a groove on a gear produced with 100% virgin powder allows the mechanism to be easily unlocked regardless of the orientation and wheel-shaft thicknesses. The application of a specific evolutionary profile independent of the diameter of the reference circle on vertically oriented gears guarantees rotation continuity while preserving the functionality of the assembled mechanism.

In the literature, there are various studies on material aging and reuse in the PBF-LB/P process, mainly focused on the powder deterioration mechanism, powder fluidity, microstructure and mechanical properties of the parts and process parameters. This study, instead, was focused on the functioning of gears, which represent one of the applications in which this technology can have great success, by analyzing the two main effects that can compromise it: recycled powder and vertical orientation during construction.

Epoxy zinc-rich coatings are widely used in harsh environments because of the long-lasting cathodic protection of steel surfaces. The purpose of this paper is to use flake zinc powder instead of the commonly used spherical zinc powder to reduce the zinc powder content.

In this paper, the authors have prepared an anticorrosive zinc-rich coating using a flake zinc powder instead of the conventional spherical zinc powder. The optimal dispersion of scaly zinc powder in zinc-rich coatings has been explored by looking at the surface and cross-sectional morphology and studying the cathodic protection time of the coating.

The final epoxy zinc-rich coating with 35 Wt.% flake zinc powder content was prepared using sand-milling dispersions. It has a similar cathodic protection time and salt spray resistance as the 60 Wt.% spherical zinc-rich coating, with a higher low-frequency impedance modulus value.

This study uses flake zinc powder instead of the traditional spherical zinc powder. This reduces the amount of zinc powder in the coating and improves the corrosion resistance of the coating.