Papers by Keyword: Relative Density

Abstract: This study provides a comprehensive investigation into the effects of different scanning parameter combinations—specifically scanning speed and hatch distance—on the material properties of IN939 fabricated using the powder bed fusion-laser beam (PBF-LB) process under a constant volumetric energy density (VED). Despite the fixed VED, the fabricated samples experienced different thermal cycles, resulting in distinct microstructural features and corresponding variations in material performance. In-situ infrared monitoring indicated that the sample with the narrowest hatch distance and highest scanning speed (Sample 1) reached the highest normalized temperatures with intense heat accumulation, whereas wider hatch distances (Sample 3) promoted lower and more stable temperature distributions. The results revealed that the intermediate parameter set (Sample 2) achieved the highest relative density (99.29%) and the lowest surface roughness. In contrast, both the narrowest and widest hatch spacing combinations promoted increased porosity, primarily consisting of lack-of-fusion (LoF) and gas pores. Electron backscatter diffraction (EBSD) analysis showed that the area-weighted average grain size increased from 29.5 µm to 36.7 µm as the hatch distance increased. Texture analysis indicated generally weak crystallographic texture development, with only slight intensification of <001>//BD and <111>//BD components, attributed to the 67^o rotation strategy. Furthermore, the microhardness values demonstrated negligible variation across the samples, ranging from 356.7 ± 14.3 HV1 to 360.1 ± 10.5 HV1. This limited variation indicates that the strengthening behavior was predominantly governed by the combined influence of defect density and matrix–defect interactions, rather than being directly correlated with grain size.

Abstract: Microbially induced calcite precipitation (MICP) is a promising alternative method for improving the geotechnical properties of granular soils. The effectiveness of the MICP technique depends on several variables, including relative density and temperature. The objective of this study was to determine the effect of different initial relative densities and ambient temperature ranges on the effectiveness of MICP. After 300 and 600 hours of MICP treatment, with injection cycles occurring every 12 hours, the specimens with a relative density of 34.5% were found to be effectively cemented. In contrast, specimens with a relative density of 59.8% were found to be less cemented. A greater percentage of specimens (52.4%) were cemented at warmer ambient temperatures (20-28°C), compared to only 15.7% at cooler temperatures (16-24°C). These results suggest that the looser soil matrix and warmer temperatures facilitated CaCO₃ precipitation and resulted in greater cementation.

Abstract: Investigating how two different ceramic additives affect the microstructure and nanomechanical characteristics of the Ti6Al4V matrix forms the goal of this work. Under 50 MPa pressure, 10 min dwell time, and 100 °C/min sintering rate at 950 °C, a pulsed electric current sintering process, or PECS, was used. An XRD spectrometer was used to examine the phases, and SEM-EDS was used to examine the bulk morphology of the starting powders and sintered composites. The fabricated Cs1, Cs2, and Cs3 composites attained theoretical densities of 99.74, 98.90, and 96.7%, respectively, above 96.22% of unreinforced Ti-alloy. The SEM analysis showed an even dispersion of the ceramic reinforcements in the matrix of Ti6Al4V, with the characteristics of porous craters in all the samples. Of the three composite samples, Cs1 showed the highest elastic modulus, micro, and nanohardness absolute values of 173 GPa, 796 MPa, and 8942 MPa, respectively, as compared to the unreinforced titanium alloy of 114 GPa, 589 MPa, and 6466 MPa. It was thought that the improved mechanical properties of the sintered composites were due to the production of intermediate phases of Ti₂N and SiO₂ during the sintering process. The materials improvement stands at approximately 30% of the unreinforced Ti-alloy.

Abstract: The micro-nanoBaTiO₃ ceramics of different sizes have been prepared simply and controllably via a self-assembly sintering method. The effects and scopes of the application of this method in the controllable synthesis of the micro-nanoBaTiO₃ ceramics are investigated. Through the given size of BaTiO₃ powders and the combination way, the ceramics with different grain sizes, such as 400~500 nm, can be controllably synthesized. Therefore, the use of this method is conducive to the realization of the controllable synthesis of the micro-nanoBaTiO₃ ceramics.

Abstract: Zinc Selenide ceramic was successfully fabricated by spark plasma sintering in the study. The ZnSe raw powders were handled with two different methods such as grinding and planetary ball milling, respectively. The relative density, microstructure and transmittance of the ZnSe ceramic sintered under the same sintering parameter with two type powders was investigated. The results shown that the performance of the powder processed by ball milling was more effective than that by grinding. Furthermore, the maximum relative density can reach 99.8% when the ZnSe powder treated by ball milling were sintered at 950 oC for 30 min with the heating rate of 10 oC/min under 100 MPa.

Abstract: Tritium breeder blanket has been considered as one of the most important components of thermonuclear fusion reactor. Recently, Li₄SiO₄ has been regarded as one of the favored ceramics breeders as it exhibits excellent tritium release properties. In order to further improve the comprehensive properties of Li₄SiO₄ pebbles, the grain size and crush load of Li₄SiO₄ pebbles doped with Y₂O₃ and Nb₂O₅ were systematically studied in this work. The results showed that the relative density of Li₄SiO₄ pebbles was increased to 87.2% and the crush load was increased from 43N to 48N when Y₂O₃ doping was used. In view of inhibiting grain growth and increasing the crush load and relative density of Li₄SiO₄ pebbles, the effect of Nb₂O₅ doping was better than that of Y₂O₃ doping.

Abstract: In the present study an attempt is made to evaluate the ultimate horizontal pullout capacity of group of two square anchors embedded in medium dense sand by conducting laboratory model tests. The size of the model box used in the present study is 1.2m lengthx0.75m width and 1.5m height. A series of experiments were conducted on single and group of anchors subjected to horizontal pullout load on mild steel square plates of size 10 cm and 15 cm were used .Clean dry local river sand was used in the present study. All the tests were carried out on dry clean sand with a relative density of 55% corresponding to medium dense state. The raining technique was adopted to prepare the sample in the model box to achieve the desired density. In the present study the ratio of H/B is equal to 5 and 6; where H = depth of embedment from top of tank to bottom of lower anchor, B=width of anchor. The parameter S/B is equal to 0,1,2; where S = clear spacing between the anchor, and B= width of anchor. It was found from the present study as H/B ratio increases the pull out capacity increases and also for each H/B ratio as the S/B ratio increases pull out capacity decreases due to decrease in passive resistance. In the present study the group efficiency factor was found which is defined as the ratio pull out capacity of group of anchors to the pull out capacity of single anchor. It was found that the group efficiency factor was found to be greater than 1 and further as S/B ratio increases the group efficiency factor decreases for same H/B ratio. Also as H/B increases the efficiency factor also increases. The anchor breakout factor (N_γ) was also found which tends to increase with increase in depth of embedment and decreases with clear spacing between the anchors. The present data was compared with that of published literature on single anchors and it was found to compare well.

Abstract: Powder-bed based additive manufacturing techniques are of high interest for the medical sector and recent trial studies have shown their feasibility. Due to the rapid improvements made in the machinery and the related changes in the type and characteristics of the utilized power source, optimizations regarding the fabrication parameters tend to differ amongst various machines. In this study, a parameter optimization was undertaken for a biocompatible dental CoCrMo alloy on a SLM 280HL machine, featuring a 400 W fibre laser. It was shown that the availability of higher laser powers enables a more energy efficient fabrication. Moreover, parameter sets for fast and economic fabrication, as well as for high density and fine-grained microstructure, were defined.

Abstract: The aim of this research paper is to fabricate a Fe-TiC composite by a novel and simple manufacturing method. The latter is based on two cumulative processes; a conventional sintering (transient liquid phase sintering) and a hot forging with steam hammer respectively. The blinder phase of the studied simples is varied from carbon steel to high alloy steel using alloying additive powders. The obtained outcomes showed that after the sintering process, the relative density of the performed simples is improved from 86% to 95.8% without any densification process. Otherwise, in order to ensure maximum densification and enhance in addition the solubility of the alloying additives the hot forging process is then applied. Indeed, the final obtained composite product is a TiC-strengthened steel with a relative density around 99% (about 6.5 g/cm³ of density) wherein 30% (wt.) of spherical and semi-spherical TiC particles are homogeneously distributed in the metal matrix.

Abstract: For the study of the metal-rubber which is a new material used as damper component. The compression mechanical properties of metal-net rubber were studied. Through the static compression test of metal-net rubber, the influence of some factors such as: compression amount, relative density, wire diameter and bearing area. The method is variable-controlling. Experimental results show that along with the increase of the amount of compression, the nonlinear mechanical properties of metal-net rubber boosts; with the increase of relative density, the compressive capacity of metal-net rubber improves. The wire diameter influences the nonlinear mechanical properties of metal-net rubber, the larger the wire diameter, the compressive capacity is higher; the bearing area is greater, the compressive capacity and energy dissipation performance are better.