Correlation Between Mechanical Properties and Particle Size of Fiber-Reinforced Selective Laser Sintering–Precoated Sand Molds

PurposeThe range of applications of the currently available biomass selective laser sintering (SLS) parts is limited and low-quality. This study aims to demonstrate the effects of the various processing parameters on the dimensional accuracy, bending strength, tensile strength, density and impact strength of the Prosopis chilensis/polyethersulfone (PES) composites (PCPCs) that were produced by SLS. The various processing parameters are laser power, scan speed, preheating temperature, scan spacing and layer thickness. In addition, the authors’ studied the effects of PCP particle size on the mechanical properties of the PCPCs.Design/methodology/approachThe PCPC specimens were printed using an AFS SLS machine (additive manufacturing). The bending, tensile and impact strengths of the specimens were measured using a universal tensile tester. The dimensional accuracy of the bending specimens was determined by a Vernier caliper. The formability of the PCPC at various mixing ratios of the raw materials was earlier investigated by single-layer sintering experiments (Idriss et al., 2020b). The microstructure and particle distribution of the various PCPC specimens were analyzed by scanning electron microscopy (SEM).FindingsThe mechanical strengths (bending, tensile and impact strengths and density) and the dimensional accuracy of the PCPC SLS parts were directly and inversely proportional, respectively, to the laser power and preheating temperature. Furthermore, the mechanical strengths and dimensional accuracy of the PCPC SLS parts were inversely and directly proportional, respectively, to the scanning speed, scan spacing and layer thickness.Practical implicationsPCPC is an inexpensive, energy-efficient material that can address the drawbacks of the existing SLS parts. It is also eco-friendly because it lowers the pollution and CO2 emissions that are associated with waste disposal and SLS, respectively. The optimization of the processing parameters of SLS in this study produced high-quality PCPC parts with high mechanical strengths and dimensional accuracy that could be used for the manufacture of the roof and wooden floors, construction components and furniture manufacturing.Originality/valueTo the best of the authors’ knowledge, this study is among the first to elucidate the impact of the various SLS processing parameters on the mechanical properties and dimensional accuracy of the sintered parts. Furthermore, novel PCPC parts were produced in this study by SLS.

The aim and objectives of the study are to establish the influence of different dosages of basalt and polypropylene fibers in a wide range of concentrations on the main physical and mechanical indicators of road cement concrete based on Portland cement with its partial replacement by ground blast furnace slag and based only on clinker Portland cement. The article presents the results of the influence of different dosages of basalt fibers and polypropylene fibers in a wide range of concentrations on the physical and mechanical properties of road cement concrete. It was found that the introduction of polypropylene fibers and basalt fibers has almost no effect on the compressive strength of cement concrete. Based on experimental studies, the concentration of polypropylene and basalt fibers was determined, which corresponds to the maximum tensile strength in bending of cement concrete. This concentration is 0.9-1.0 kg/m3 of polypropylene fiber and 15.0-16.0 kg/m3 of basalt fiber. A change in the average density of cement concretes with the addition of polypropylene fibers and basalt fibers was established. The introduction of the optimal amount of polypropylene fiber (fiber) leads to higher values of the tensile strength parameter in bending of road cement concrete compared to cement concrete based on basalt fiber. The change in the strength indicators of cement concrete based on Portland cement partially replaced by ground slag with the addition of the optimal amount of polypropylene fibers and basalt fibers is similar to the change in these indicators of cement concrete based on purely clinker Portland cement.

A solid freeform fabrication (SFF) system using selective laser sintering (SLS) is currently recognized as a leading process and SLS extends the application to machinery and automobiles due to the various materials employed. In order to develop a more elaborate and rapid system for fabricating large objects compared to existing SLS, this study employs a new selective dual-laser sintering (SDLS) process. It contains a 3-axis, dynamic focusing scanner system for scanning large areas instead of the existing fθ lens used in commercial SLS. Therefore, the unique scanning path generation is necessary to eliminate the factors of quality deterioration in case of fabricating larger objects. Also, this paper will address development of a SFF system which employs the dual laser system and the unique scanning device. In the SLS, the sintering temperature, laser beam power and layer thickness have a great influence on sintering of the polymer. Experiments were performed to evaluate the effect of a scanning path and fabrication parameters on sintering process and to fabricate the various 3D objects using polymer.A solid freeform fabrication (SFF) system using selective laser sintering (SLS) is currently recognized as a leading process and SLS extends the application to machinery and automobiles due to the various materials employed. In order to develop a more elaborate and rapid system for fabricating large objects compared to existing SLS, this study employs a new selective dual-laser sintering (SDLS) process. It contains a 3-axis, dynamic focusing scanner system for scanning large areas instead of the existing fθ lens used in commercial SLS. Therefore, the unique scanning path generation is necessary to eliminate the factors of quality deterioration in case of fabricating larger objects. Also, this paper will address development of a SFF system which employs the dual laser system and the unique scanning device. In the SLS, the sintering temperature, laser beam power and layer thickness have a great influence on sintering of the polymer. Experiments were performed to evaluate the effect of a scanning path and fa...

Objectives: Utilization of steel fiber increases concrete strength and ductility however, the cost of steel fiber is high and ultimately leads to an increase in the cost of concrete. Basalt fiber is a new type of fiber with high strength and toughness and can effectively replace the place of steel fibers. In this paper, concrete reinforced with polypropylene fibers and basalt fibers was tested for its mechanical properties and compared with the same predicted through a simulated model created by the Artificial Neural Network. Methods: The percentage of polypropylene fiber was kept at 0.25%, and different amounts of basalt fiber were added as 0%, 0.25%, 0.5%, 0.75%, and 1%. Based on traditional testing methods compressive strength, tensile strength, and flexural strength of normal concrete, Fiber reinforced concrete and Hybrid fiber reinforced concrete have been found. To forecast the concrete qualities, the model was simulated after the datasets were trained using a neural network fitting tool. Findings: In comparison to concrete that had only 0.25% polypropylene fiber, a hybrid fiber-reinforced concrete mix including 0.5% basalt fiber and 0.25% polypropylene fiber demonstrated a 9.69% improvement in compressive strength. In comparison to the concrete made only of polypropylene, the mix containing 0.25% polypropylene fiber and 0.75% basalt fiber showed a 26.12% increase in flexural strength and a 39.25% increase in split tensile strength. The error percentage between predicted and experimental values is below 10%. Novelty: Utilization of basalt fiber in concrete is very rare and this proposed work focused on the hybridization of basalt fiber in the place of steel fibers, which is prone to corrosion and reduces the cost of material effectively. The concrete's flexural and tensile strengths were significantly increased by the addition of basalt fibers. The mechanical characteristics of hybrid fiber-reinforced concrete are well predicted by the simulated ANN model. Keywords: Basalt fiber, Polypropylene fiber, Artificial Neural network, Fiber reinforced concrete, Hybridization

This study investigates on the impact of basalt fiber reinforcement concrete in protected building and structures. Basalt fibers, derived from the melting of basalt rock at temperatures ranging from 1,500 to 1700°C, are recognized as sustainable and environmentally friendly fiber materials. Various studies have revealed differing optimal percentages of basalt fibers for enhancing the mechanical and chemical properties of concrete. The objectives of this paper are to investigate the effects of basalt fibre reinforcement on mechanical properties like tensile, compressive, and bending strengths. Additionally, performance indicators like void content, water absorption, chloride ion permeability, alkali and slag resistance, temperature stability, shrinkage characteristics, and abrasion resistance will be evaluated. Basalt fibre is typically utilised to increase the mechanical properties and durability of concrete, which has an impact in the effect on protected buildings and structures. The findings indicate that the most effective percentage range for improving mechanical properties lies between 0.1% and 0.3% of basalt fibers. Notably, concrete reinforced with basalt fibers demonstrates superior mechanical and chemical performance in alkaline environments compared to other fiber types. Moreover, the addition of 0.5% basalt fibers to concrete has been shown to significantly reduce chloride ion penetration, as evidenced by a decrease in RCPT load from 2,500 (C) to 1900 (C), indicative of enhanced chloride resistance. Reinforced concrete containing basalt fibers exhibits remarkable temperature resistance, withstanding temperatures exceeding 800°C due to its high-water absorption capacity. Additionally, basalt fibers exhibit resilience at temperatures up to 200°C. However, it is noted that the introduction of 0.14% basalt fibers leads to a slight increase in water absorption from 4.08 to 4.28. In general, basalt fibres are beneficial to many aspects of concrete; they strengthen resistance to temperature, alkali, acid exposure, and chloride while also improving mechanical qualities such as bending and tensile strength. The development of basalt fibres that extend building lifespans and improve concrete quality for structural engineering applications is making encouraging strides, according to all the results.

In this study, mechanical properties such as tensile, flexural and impact strengths of hemp/phenol formaldehyde (PF), basalt/PF and hemp/basalt hybrid PF composites have been investigated as a function of fibre loading. Hemp fibre reinforced PF composites and basalt fibre reinforced composites were fabricated with varying fibre loading i.e. 20, 32, 40, 48, 56 and 63 vol%. The hybrid effect of hemp fibre and basalt fibre on the tensile, flexural and impact strengths was also investigated for various ratio of hemp/basalt fibre loading such as 1:0, 0.95:0.05, 0.82:0.18, 0.68:0.32, 0.52:0.48, 0.35:0.65, 0.18:0.82 and 0:1. Total fibre loading of the hybrid composites was 40 vol%. The results showed that the tensile strength and elongation at break increase with increasing fibre loading up to 40 vol% and decrease above this value for hemp fibre reinforced PF composite. Similar trend was observed for flexural strength and the maximum value was obtained for 48 vol% hemp fibre loading. Impact strength of hemp/PF composite showed a regular trend of increase with increasing fibre loading up to 63 vol%. Tensile strength, flexural strength and impact strength values of basalt/PF composites were found to be lower compared to hemp/PF composites. The tensile strength and elongation at break of basalt/PF composite increased by incorparation of basalt fibre up to 32 vol% and decreased beyond this value. Flexural strength of basalt/PF composite decreased linearly with fibre loading. However, the maximum impact strength was obtained for 48 vol% basalt fibre loading. For hemp/basalt hybrid PF composite, the tensile strength decreased with increasing basalt fibre loading. On the other hand, the flexural and impact strengths showed large scatter. The maximum flexural strength value was obtained for 0.52:0.48 hemp/basalt ratio. Corresponding value for impact strength was obtained for 0.68:0.32 hemp/basalt fibre ratio.

The current available wood-plastic materials used for selective laser sintering (SLS) investment casting are often poor in fluidity in molten state, which is not easy to flow out the shell mold. This led to a large amount of residual ash in mold after heating and lowered the quality of the sintered parts. In this article, the Co-Polyamide (Co-PA Hotmelt adhesive) and rice husk powders (RH) were proposed as the feedstock of the rice husk (RH)/CO-PA composite (RHPA) for SLS. CO-PA with good fluidity was used as the matrix and RH powder as the additive materials. This paper aims to optimize the SLS processing parameters and determine the optimal ratio of RHPA parts manufactured by SLS. Through this work, an orthogonal experimental method of five factors and four levels was used to determine the optimum SLS parameters for the RHPA SLS test. The scan spacing, scan speed, laser power, layer thickness, and preheating temperature are chosen as main SLS affecting factors of this study. The synthesis weighted scoring methods were used to conclude the optimal combination of SLS parameters of RHPA i.e., scan spacing = 0.15mm, scan speed = 2m/s, laser power =16W, layer thickness = 0.25 mm and the preheating temperature = 74°C. Moreover, the influence of RH content on the mechanical properties, dimensional accuracy, and the residual ash content of RHPA parts was determined. When the ratio of RH powder on RHPA is 10 wt %, the bending strength of the sintered parts will reach 2 MPa. Besides, the residual ash content of RHPA parts after heating step was lower (1.1881%) and the tolerance level is CT5. Thus, the dimensional accuracy in X, Y, and Z directions of 10 wt % RHPA SLS parts is 99.79%, 98.71%, and 97.9%, respectively; and the surface of casting was smooth and clear details.

Effect of layered manufacturing techniques, alloy powders, and layer thickness on mechanical properties of Co-Cr dental alloys

Assessment of mechanical properties and microstructure of Co-Cr dental alloys manufactured by casting, milling, and 3D printing.

This study investigates the influence of basalt fiber on the rheological, mechanical, and microstructural properties of sustainable self-compacting concrete (SCC) incorporating fly ash and microsilica as supplementary cementitious materials (SCMs). Various SCC mixes were prepared, incorporating five different volume fractions of basalt fiber (0.05%, 0.1%, 0.5%, 1%, and 1.5%), along with a control mix. The rheological properties of fresh SCC were evaluated using slump flow and V-funnel flow tests. Subsequently, the mechanical properties, including compressive strength, splitting tensile strength, and flexural strength, were measured after 28 days of curing. Additionally, microstructural analysis was conducted using scanning electron microscopy (SEM) on fractured specimen surfaces. The results indicated that the inclusion of basalt fiber adversely affected the flowability of fresh SCC mixes, with increased fiber volume. However, the hardened concrete exhibited significant improvements in mechanical properties with the addition of basalt fibers. The optimal performance was observed in the SCC70-85/0.10 mix specimens, which demonstrated a 69.90% improvement in flexural strength and a 23.47% increase in splitting tensile strength compared with the control specimen. SEM analysis further revealed enhanced microstructural density in the concrete matrix containing basalt fiber. A two-factor analysis of variance (ANOVA) with repetitions was conducted to evaluate the effects of varying basalt fiber concentrations on the compressive, flexural, and tensile strengths of SCC mixes. The ANOVA results indicated significant effects for both SCC grade and basalt fiber concentration, demonstrating that each factor independently affected the compressive, tensile, and flexural strengths of SCC. These findings suggest that the incorporation of basalt fibers holds promise for extending building lifespans and enhancing concrete quality, representing a valuable advancement in structural engineering applications.

In the solid freeform fabrication (SFF) system using selective laser sintering (SLS), polyamide-12 powder is currently recognized as general materials. Polyamide-12 powder has properties as average particle size is 58µm, density is 0.59 g/cm3. The object of this study is obtained base data that some kinds of polyamide-6 powders with different shape and particle size were fabricated to investigate the formability, microstructure and mechanical properties. Especially, the particle shape distribution played an important role in the precision of fabrication. To make similar type particle size and particle shape of polyamide-12 powder, polyamide-6 powder’s particle pulverize that until it under 100um using the process of dry type low temperature. Also, polyamide-6 powders having the average size of under 100um were treated thermally in order to keep the spherical symmetry shape. And to develop a more elaborate and rapid system, this study employs a new SLS device with a 3-axis dynamic focusing scanner system instead of the existing fθ lens used in commercial SLS. Based on materials and device, experiment performed to about various sintering condition such as build room temperature, feed room temperature, scan speed, scan spacing, laser power and layer thickness.In the solid freeform fabrication (SFF) system using selective laser sintering (SLS), polyamide-12 powder is currently recognized as general materials. Polyamide-12 powder has properties as average particle size is 58µm, density is 0.59 g/cm3. The object of this study is obtained base data that some kinds of polyamide-6 powders with different shape and particle size were fabricated to investigate the formability, microstructure and mechanical properties. Especially, the particle shape distribution played an important role in the precision of fabrication. To make similar type particle size and particle shape of polyamide-12 powder, polyamide-6 powder’s particle pulverize that until it under 100um using the process of dry type low temperature. Also, polyamide-6 powders having the average size of under 100um were treated thermally in order to keep the spherical symmetry shape. And to develop a more elaborate and rapid system, this study employs a new SLS device with a 3-axis dynamic focusing scanner system i...

The hybridization of Basalt Fibers (BF) and Polypropylene Fibers (PF) in High-Strength Concrete (HSC) has immense potential to improve its mechanical properties. This paper investigates the compressive strength, tensile splitting strength, and flexural strength of HSC reinforced with single BF, single PF, and hybrid fibers. Samples from thirteen mixes (i.e., one control, four BF, four PF, and four hybrid mixes) were prepared and tested at 7, 14, and 28 days. The BF content ranged from 0.1 to 0.7%, while that of PF ranged from 0.05 to 0.3%. The results indicate that at 0.3% BF dosage, the compressive strength increased from 60.66 MPa in the control mix to 62.70 MPa (a 3.36% increase). Similarly, at a 0.1% PF dosage, it increased to 61.42 MPa (a 1.25% increase). The tensile splitting strength increased from 3.97 MPa in the control mix to 4.61 MPa (a 16.12% increase) with optimal BF, and to 4.22 MPa (a 6.30% increase) with optimal PF. Similarly, the flexural strength increased from 6.22 MPa to 7.40 MPa (an 18.97% increase) with optimal BF, and to 6.70 MPa (a 7.72% increase) with optimal PF. The optimal hybrid combination consisted of 0.3% BF and 0.1% PF, which increased the compressive strength to 64.62 MPa (a 6.53% increase) at 28 days. The tensile splitting strength and flexural strength increased by 44.33% and 29.58%, respectively. It was therefore concluded that combining both fiber types in concrete produced a positive synergistic effect. Thus, using fibers in a hybrid form is more beneficial for producing high-strength fiber-reinforced concrete.

Natural fibers, such as kenaf, hemp, and flax, also known as bast fibers, offer several benefits such as low density, carbon dioxide neutrality, and less dependence on petroleum sources. Their function as reinforcement in polymer composites offers a great potential to replace a segment of the glass fiber-reinforced polymer composites, especially in automotive components. Despite their promising benefits, they cannot meet the structural and durability demands of automobile parts because of their poor mechanical properties compared to glass fibers. The focus of this research work was the improvement of the mechanical property profile of the bast fiber reinforced polypropylene composites by hybridization with natural high-performance basalt fibers and the influence of basalt fibers coating and polymer modification at the mechanical and thermal properties of the composites. The specific tensile strength of the composite with polymer tailored coating was 39% and the flexural strength was 44% higher than the composite with epoxy-based basalt fibers. The mechanical performance was even better when the bast/basalt hybridization was done in maleic anhydride modified polymer. This led to the conclusion that basalt fibers sizing and polymer modification are the deciding factors in defining the optimal mechanical performance of the composites by influencing the fiber-matrix interaction. The composites were analyzed for their mechanical, thermal, and morphological properties. The comparison of bast/basalt hybrid composite with bast/glass fibers hybrid composite showed a 32% higher specific flexural and tensile strength of the basalt hybrid composite, supporting the concept of basalt fibers as a natural alternative of the glass fibers.

Cement is widely used as the primary binder in concrete; however, growing environmental concerns and the rapid expansion of the construction industry have highlighted the need for more sustainable alternatives. Geopolymers have emerged as promising eco-friendly binders due to their lower carbon footprint and potential to utilize industrial byproducts. Geopolymer mortar, like other cementitious substances, exhibits brittleness and tensile weakness. Basalt fibers serve as fracture-bridging reinforcements, enhancing flexural and tensile strength by redistributing loads and postponing crack growth. Basalt fibers enhance the energy absorption capacity of the mortar, rendering it less susceptible to abrupt collapse. Basalt fibers have thermal stability up to about 800–1000 °C, rendering them appropriate for geopolymer mortars designed for fire-resistant or high-temperature applications. They assist in preserving structural integrity during heat exposure. Fibers mitigate early-age microcracks resulting from shrinkage, drying, or heat gradients. This results in a more compact and resilient microstructure. Using basalt fibers improves surface abrasion and impact resistance, which is advantageous for industrial flooring or infrastructure applications. Basalt fibers originate from natural volcanic rock, are non-toxic, and possess a minimal ecological imprint, consistent with the sustainability objectives of geopolymer applications. This study investigates the mechanical and thermal performance of a geopolymer mortar composed of metakaolin and red mud as binders, with basalt powder and limestone powder replacing traditional sand. The primary objective was to evaluate the effect of basalt fiber incorporation at varying contents (0.4%, 0.8%, and 1.2% by weight) on the durability and strength of the mortar. Eight different mortar mixes were activated using sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solutions. Mechanical properties, including compressive strength, flexural strength, and ultrasonic pulse velocity (UPV), were tested 7 and 28 days before and after exposure to elevated temperatures (200, 400, 600, and 800 °C). The results indicated that basalt fiber significantly enhanced the performance of the geopolymer mortar, particularly at a content of 1.2%. Specimens with 1.2% fiber showed up to 20% improvement in compressive strength and 40% in flexural strength after thermal exposure, attributed to the fiber’s role in microcrack bridging and structural densification. Subsequent research should concentrate on refining fiber type, dose, and dispersion techniques to improve mechanical performance and durability. Examinations of microstructural behavior, long-term durability under environmental settings, and performance following high-temperature exposure are crucial. Furthermore, investigations into hybrid fiber systems, extensive structural applications, and life-cycle evaluations will inform the practical and sustainable implementation in the buildings.

The current available selective laser sintering (SLS) materials are often high in cost and limited in variety; the mechanical properties of wood-composite SLS parts are low quality, which restricts the development of SLS technology. This article aims to optimize the SLS processing parameters to enhance the mechanical properties of the Prosopis chilensis powder (PCP)/polyethersulfone (PES) composite (PCPC) part fabricated via SLS. The PCP and PES powder were proposed as the feedstock of the PCPC powder bed for SLS. First, the thermal decomposition and glass transition temperatures (Tg) of PCP and PES powder were estimated to reduce the produced PCPC parts from warping and deformation during SLS. An orthogonal experimental methodology with five factors and four levels was used to optimize the SLS parameters for the PCPC SLS test. The scanning speed, preheating temperature, and laser power are selected as the main affecting factors on this study. The influence of these factors on dimension accuracies, bending and tensile strengths, and surface roughness quality of the produced PCPC parts was studied. The PCPC particle distribution and microstructure were inspected via scanning electron microscopy. Furthermore, the synthesis weighted scoring methods were utilized to determine the optimal SLS processing parameters of the produced PCPC parts. The combined results of tests showed that the optimal SLS parameters were as follows: the scanning speed is 1.8 m/s, preheating temperature is 80°C, and the laser power is 12 W. Thus, the quality of PCPC SLS parts was significantly enhanced when the optimal parameters were utilized in the SLS process. This article provided the main reference values of SLS parameters of the PCPC. To further enhance the surface roughness quality and mechanical strengths, the postprocessing infiltration with wax was introduced; after wax infiltration, the surface roughness and mechanical strengths were significantly improved.