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1 – 10 of 732Mandeep Singh, Khushdeep Goyal and Deepak Bhandari
The purpose of this paper is to evaluate the effect of titanium oxide (TiO2) and yttrium oxide (Y2O3) nanoparticles-reinforced pure aluminium (Al) on the mechanical properties of…
Abstract
Purpose
The purpose of this paper is to evaluate the effect of titanium oxide (TiO2) and yttrium oxide (Y2O3) nanoparticles-reinforced pure aluminium (Al) on the mechanical properties of hybrid aluminium matrix nanocomposites (HAMNCs).
Design/methodology/approach
The HAMNCs were fabricated via a vacuum die-assisted stir casting route by a two-step feeding method. The varying weight percentages of TiO2 and Y2O3 nanoparticles were added as 2.5, 5, 7.5 and 10 Wt.%.
Findings
Scanning electron microscope images showed the homogenous dispersion of nanoparticles in Al matrix. The tensile strength by 28.97%, yield strength by 50.60%, compression strength by 104.6% and micro-hardness by 50.90% were improved in HAMNC1 when compared to the base matrix. The highest values impact strength of 36.3 J was observed for HAMNC1. The elongation % was decreased by increasing the weight percentage of the nanoparticles. HAMNC1 improved the wear resistance by 23.68%, while increasing the coefficient of friction by 14.18%. Field emission scanning electron microscope analysis of the fractured surfaces of tensile samples revealed microcracks and the debonding of nanoparticles.
Originality/value
The combined effect of TiO2 and Y2O3 nanoparticles with pure Al on mechanical properties has been studied. The composites were fabricated with two-step feeding vacuum-assisted stir casting.
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Mandeep Singh, Deepak Bhandari and Khushdeep Goyal
This study aims to examine the corrosion and flexural behaviour of advanced hybrid aluminium matrix nanocomposites (HAMNCs) made with a vacuum-assisted stir die casting (two-layer…
Abstract
Purpose
This study aims to examine the corrosion and flexural behaviour of advanced hybrid aluminium matrix nanocomposites (HAMNCs) made with a vacuum-assisted stir die casting (two-layer feeding) and reinforced with titanium oxide (TiO2) and yttrium oxide (Y2O3) nanoparticles. The previous researchers have shown that TiO2 and Y2O3 nanoparticles make aluminium composites much more resistant to corrosion and wear.
Design/methodology/approach
Salt spray corrosion tests were done on the samples over time as well as the pre-and post-corrosion morphology of the test samples was also investigated. The density, porosity and energy dispersive X-ray of the fabricated samples were observed.
Findings
It was observed that a lower corrosion rate of 0.127 mils/year and 0.573 mils/year was seen in the Al/5 Wt.%TiO2/5 Wt.%Y2O3 (HAMNC1) and Al/7.5 Wt.%TiO2/2.5 Wt.%Y2O3 (HAMNC3), respectively. It was evident from the results that the pores and densities of the samples varied with the filler concentrations and matrix filler wettability. HAMNC1 has the lowest values of density and porosity at 2.568 g/cm3 and 9.91%, respectively. At the same time, a significant improvement in the flexural strength of 72 N/mm2 was also seen in the HAMNC1 configuration.
Practical implications
The proposed hybrid samples are well suited for aerospace and automobile structural components such as brake drums, discs, engine cylinders and fins.
Originality/value
The mixed influence evaluation of TiO2 and Y2O3 nanoparticles with pure Al on composite samples has not been studied. This research aims to examine the combined influence of nanoparticles on the corrosion aspects of two-step feeding vacuum stir casted products, as well as their morphology.
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Ulrich Gabbert, Stefan Ringwelski, Mathias Würkner and Mario Kittsteiner
Pores and shrink holes are unavoidable defects in the die-casting mass production process which may significantly influence the strength, fatigue and fracture behaviour as well as…
Abstract
Purpose
Pores and shrink holes are unavoidable defects in the die-casting mass production process which may significantly influence the strength, fatigue and fracture behaviour as well as the life span of structures, especially if they are subjected to high static and dynamic loads. Such defects should be considered during the design process or after production, where the defects could be detected with the help of computed tomography (CT) measurements. However, this is usually not done in today's mass production environments. This paper deals with the stress analysis of die-cast structural parts with pores found from CT measurements or that are artificially placed within a structure.
Design/methodology/approach
In this paper the authors illustrate two general methodologies to take into account the porosity of die-cast components in the stress analysis. The detailed geometry of a die-cast part including all discontinuities such as pores and shrink holes can be included via STL data provided by CT measurements. The first approach is a combination of the finite element method (FEM) and the finite cell method (FCM), which extends the FEM if the real geometry cuts finite elements. The FCM is only applied in regions with pores. This procedure has the advantage that all simulations with different pore distributions, real or artificial, can be calculated without changing the base finite element mesh. The second approach includes the pore information as STL data into the original CAD model and creates a new adapted finite element mesh for the simulation. Both methods are compared and evaluated for an industrial problem.
Findings
The STL data of defects which the authors received from CT measurements could not be directly applied without repairing them. Therefore, for FEM applications an appropriate repair procedure is proposed. The first approach, which combines the FEM with the FCM, the authors have realized within the commercial software tool Abaqus. This combination performs well, which is demonstrated for test examples, and is also applied for a complex industrial project. The developed in-house code still has some limitations which restrict broader application in industry. The second pure FEM-based approach works well without limitations but requires increasing computational effort if many different pore distributions are to be investigated.
Originality/value
A new simulation approach which combines the FEM with the FCM has been developed and implemented into the commercial Abaqus FEM software. This approach the authors have applied to simulate a real engineering die-cast structure with pores. This approach could become a preferred way to consider pores in practical applications, where the porosity can be derived either from CT measurements or are artificially adopted for design purposes. The authors have also shown how pores can be considered in the standard FEM analysis as well.
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Yuejian Zhou, Xiaoshan Liu, Guoqiu He, Zhiqiang Zhou, Yiping Liao, Yinfu Liu and Xiaojun Xu
This paper aims to investigate the effect of Cu content and T6 heat treatment on the mechanical properties and the tribological performance of SiCp/Al-Si-Cu-Ni-Mg hybrid…
Abstract
Purpose
This paper aims to investigate the effect of Cu content and T6 heat treatment on the mechanical properties and the tribological performance of SiCp/Al-Si-Cu-Ni-Mg hybrid composites at an elevated temperature.
Design/methodology/approach
The stir casting method was used to synthesize SiCp/Al-12Si-xCu-1Ni-1Mg (x = 2, 3, 3.5, 4, 4.5, 5 Wt.%) composites containing 20 vol% SiC. The hardness and tensile strength of the aluminum matrix composites (AMCs) at room temperature and elevated temperature were studied, and the wear mechanism was investigated using scanning electron microscopic and energy dispersive spectroscopy.
Findings
Results indicate that the hardness and tensile strength of the AMCs are affected significantly by T6 heat treatment and Cu content. The high-temperature friction and wear mechanism of AMCs is the composite wear mechanism of oxidation wear, adhesion wear, abrasive wear, peeling wear, high-temperature softening and partial melting. Among them, adhesion wear, high-temperature matrix softening and local melting are the main wear mechanisms.
Originality/value
The influence mechanism of Cu content on the hardness, tensile strength and high temperature resistance of AMCs was explained by microstructure. And the results further help to explore the application of AMCs in high temperature.
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Mandeep Singh, Deepak Bhandari and Khushdeep Goyal
The purpose of this paper is to examine the mechanical characteristics and optimization of wear parameters of hybrid (TiO2 + Y2O3) nanoparticles with Al matrix using squeeze…
Abstract
Purpose
The purpose of this paper is to examine the mechanical characteristics and optimization of wear parameters of hybrid (TiO2 + Y2O3) nanoparticles with Al matrix using squeeze casting technique.
Design/methodology/approach
The hybrid aluminium matrix nanocomposites (HAMNCs) were fabricated with varying concentrations of titanium oxide (TiO2) and yttrium oxide (Y2O3), from 2.5 to 10 Wt.% in 2.5 Wt.% increments. Dry sliding wear test variables were optimized using the Taguchi method.
Findings
The introduction of hybrid nanoparticles in the aluminium (Al) matrix was evenly distributed in contrast to the base matrix. HAMNC6 (5 Wt.% TiO2 + 5 Wt.% Y2O3) reported the maximum enhancement in mechanical properties (tensile strength, flexural strength, impact strength and density) and decrease in porosity% and elongation% among other HAMNCs. The results showed that the optimal combination of parameters to achieve the lowest wear rate was A3B3C1, or 15 N load, 1.5 m/s sliding velocity and 200 m sliding distance. The sliding distance showed the greatest effect on the dry sliding wear rate of HAMNC6 followed by applied load and sliding velocity. The fractured surfaces of the tensile sample showed traces of cracking as well as substantial craters with fine dimples and the wear worn surfaces were caused by abrasion, cracks and delamination of HAMNC6.
Originality/value
Squeeze-cast Al-reinforced hybrid (TiO2+Y2O3) nanoparticles have been investigated for their impact on mechanical properties and optimization of wear parameters.
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Increasing utilisation of the properties of hardness, corrosion resistance and electrical insulation has taken place rapidly in recent years. Still scope exists for further…
Abstract
Increasing utilisation of the properties of hardness, corrosion resistance and electrical insulation has taken place rapidly in recent years. Still scope exists for further development of anodised aluminium as knowledge of the mechanism involved grows. In the first of this two‐part article the author deals mainly with bright and conventional architectural anodising.
Mariusz Sobolak and Grzegorz Budzik
The purpose of this paper is to determine the instantaneous contact area in a gearbox using rapid prototyping.
Abstract
Purpose
The purpose of this paper is to determine the instantaneous contact area in a gearbox using rapid prototyping.
Design/methodology/approach
The determination of the contact area utilizes one of the RP techniques, i.e. stereolithography. Stereolithography enables the making of gears with complex profiles, which are difficult to obtain by means of other machining methods. A model of a bevel gearbox with Gleason spiral generated modify roll (Gleason SGM) gears with circular‐arc profiles of teeth is applied as an example for testing. A prototype of the gearbox was made using SLA 250 apparatus.
Findings
Correct mating of gears and their kinematical precision depend on the shape and size of the instantaneous contact area, as well as changes during the turning of gears. Contact between gear surfaces of a geometrically ideal gearbox occurs at a point or line, but, because of a deformability of mating flanks teeth, in reality it is always a certain surface. This paper presents research on the instantaneous contact area with area on the surface of a flank tooth, which is in contact with the mating surface of another tooth at a specific moment.
Originality/value
The described method in the paper enables a dynamic determination of the mating area gearbox. Existing experimental methods enable only a static observation of the mating area. A stand test was built and enables an exact meshing of mating gears. Gears were made of transparent material, SL‐5170, which enables observation of the instantaneous contact area.
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Asserts that developments in management of technology (MOT) deserve more attention than they currently receive in relation to management of quality. Argues that organisations, or…
Abstract
Asserts that developments in management of technology (MOT) deserve more attention than they currently receive in relation to management of quality. Argues that organisations, or groupings of organisations, that recognise the consumer potential of the new technologies, and learn how to deliver them, will be the total quality performers of the new millennium. Considers that the pace of technological change is far faster than other movements in competitive focus. Believes that the way forward is for industry to achieve quantum leaps, not incremental improvement in customer‐ perceived quality, to adopt new materials and processes, achieved by matching science push with market pull; and, finally, undertaking new alliances and partnerships and a total system view.
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Jie Wan, Biao Chen, Jianghua Shen, Katsuyoshi Kondoh, Shuiqing Liu and Jinshan Li
The metallic alloys and their components fabricated via laser powder bed fusion (LPBF) suffer from the microvoids formed inevitably due to the extreme solidification rate during…
Abstract
Purpose
The metallic alloys and their components fabricated via laser powder bed fusion (LPBF) suffer from the microvoids formed inevitably due to the extreme solidification rate during fabrication, which are impossible to be removed by heat treatment. This paper aims to remove those microvoids in as-built AlSi10Mg alloys by hot forging and enhance their mechanical properties.
Design/methodology/approach
AlSi10Mg samples were built using prealloyed powder with a set of optimized LPBF parameters, viz. 350 W of laser power, 1,170 mm/s of scan speed, 50 µm of layer thickness and 0.24 mm of hatch spacing. As-built samples were preheated to 430°C followed by immediate pressing with two different thickness reductions of 10% and 35%. The effect of hot forging on the microstructure was analyzed by means of X-ray diffraction, scanning electron microscopy, electron backscattered diffraction and transmission electron microscopy. Tensile tests were performed to reveal the effect of hot forging on the mechanical properties.
Findings
By using hot forging, the large number of microvoids in both as-built and post heat-treated samples were mostly healed. Moreover, the Si particles were finer in forged condition (∼150 nm) compared with those in heat-treated condition (∼300 nm). Tensile tests showed that compared with heat treatment, the hot forging process could noticeably increase tensile strength at no expense of ductility. Consequently, the toughness (integration of tensile stress and strain) of forged alloy increased by ∼86% and ∼24% compared with as-built and heat-treated alloys, respectively.
Originality/value
Hot forging can effectively remove the inevitable microvoids in metals fabricated via LPBF, which is beneficial to the mechanical properties. These findings are inspiring for the evolution of the LPBF technique to eliminate the microvoids and boost the mechanical properties of metals fabricated via LPBF.
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This paper gives a review of the finite element techniques (FE) applied in the area of material processing. The latest trends in metal forming, non‐metal forming, powder…
Abstract
This paper gives a review of the finite element techniques (FE) applied in the area of material processing. The latest trends in metal forming, non‐metal forming, powder metallurgy and composite material processing are briefly discussed. The range of applications of finite elements on these subjects is extremely wide and cannot be presented in a single paper; therefore the aim of the paper is to give FE researchers/users only an encyclopaedic view of the different possibilities that exist today in the various fields mentioned above. An appendix included at the end of the paper presents a bibliography on finite element applications in material processing for 1994‐1996, where 1,370 references are listed. This bibliography is an updating of the paper written by Brannberg and Mackerle which has been published in Engineering Computations, Vol. 11 No. 5, 1994, pp. 413‐55.
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