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1 – 10 of over 2000
Article
Publication date: 18 February 2022

Jian Li, Aboubaker Idriss Bolad, Yanling Guo, Yangwei Wang, Elkhawad Ali Elfaki, Shareef Aldoom Abdallah Adam and Gafer Abd Alhamid Mohammad Ahmed

The 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…

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Abstract

Purpose

The 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/approach

The 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).

Findings

The 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 implications

PCPC 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/value

To 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.

Article
Publication date: 23 June 2021

Radhwan Bin Hussin, Safian Bin Sharif, Shayfull Zamree Bin Abd Rahim, Mohd Azlan Bin Suhaimi, Mohd Tanwyn Bin Mohd Khushairi, Abdellah Abdellah EL-Hadj and Norshah Afizi Bin Shuaib

Rapid tooling (RT) integrated with additive manufacturing technologies have been implemented in various sectors of the RT industry in recent years with various kinds of…

Abstract

Purpose

Rapid tooling (RT) integrated with additive manufacturing technologies have been implemented in various sectors of the RT industry in recent years with various kinds of prototype applications, especially in the development of new products. The purpose of this study is to analyze the current application trends of RT techniques in producing hybrid mold inserts.

Design/methodology/approach

The direct and indirect RT techniques discussed in this paper are aimed at developing a hybrid mold insert using metal epoxy composite (MEC) in increasing the speed of tooling development and performance. An extensive review of the suitable development approach of hybrid mold inserts, material preparation and filler effect on physical and mechanical properties has been conducted.

Findings

Latest research studies indicate that it is possible to develop a hybrid material through the combination of different shapes/sizes of filler particles and it is expected to improve the compressive strength, thermal conductivity and consequently increasing the hybrid mold performance (cooling time and a number of molding cycles).

Research limitations/implications

The number of research studies on RT for hybrid mold inserts is still lacking as compared to research studies on conventional manufacturing technology. One of the significant limitations is on the ways to improve physical and mechanical properties due to the limited type, size and shape of materials that are currently available.

Originality/value

This review presents the related information and highlights the current gaps related to this field of study. In addition, it appraises the new formulation of MEC materials for the hybrid mold inserts in injection molding application and RT for non-metal products.

Details

Rapid Prototyping Journal, vol. 27 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 16 May 2019

Muhamad Hasif Hussin, Nor Hazurina Othman and Mohd. Haziman Wan Ibrahim

This paper aims to investigate the use of calcined mussel shell (CMS) ash–cement mix in concrete that is found to increase the concrete resistance against carbonation.

Abstract

Purpose

This paper aims to investigate the use of calcined mussel shell (CMS) ash–cement mix in concrete that is found to increase the concrete resistance against carbonation.

Design/methodology/approach

The deposited ash from the calcination of the mussel shells at 1000°C was used to replace the ordinary Portland cement at 5 and 7 per cent of the cement weight. The test results from the control concrete specimens were compared to the test results from the experimental concrete specimens to analyse the effects due to the said replacements. Carbonation was carried out naturally in the environment where the concentration of the carbon dioxide gas was at 0.03 per cent, the relative humidity of 65 per cent and the temperature of 27°C for a maximum period of 120 days. Measurement of carbonation depth was taken in accordance to the BS EN 13295: 2004. The carbonation resistance of the concrete was assessed based on the degree of compliance with the common design life requirement of 50 years. The filler effect from the CMS was verified using the capillary absorption test (ASTM C1585: 2013) and the electron microscope.

Findings

Experimental concrete specimens containing 5 and 7 per cent of the CMS ash demonstrated better carbonation resistance compared to the control concrete specimens with a minimum attainable design life of 56 years which can reach a maximum of 62 years. Capillary absorption test results indicated that the concrete pores have been effected by the said filler effect and visual observation from the electron microscope confirmed, solidifying the statement.

Originality/value

The CMS ash is proven to contribute to the concrete’s resistance against carbonation. Also, the CMS ash is synthesized from waste materials which have contributed to the application of the green material in the concrete technology.

Details

Journal of Engineering, Design and Technology , vol. 17 no. 5
Type: Research Article
ISSN: 1726-0531

Keywords

Article
Publication date: 14 March 2016

Kezban Banu Sugozu, Behcet Daghan, Ahmet Akdemir and Necati Ataberk

Among the components used for a car brake lining, the chemical and structural properties of the abrasives, jointly with the morphology and size of the particles influence…

Abstract

Purpose

Among the components used for a car brake lining, the chemical and structural properties of the abrasives, jointly with the morphology and size of the particles influence the friction parameters and stability of the composite. This paper aims to investigate the effect of nano SiO2 particles in brake pads on friction and wear properties.

Design/methodology/approach

In this paper, the effects of SiO2 (Silica) particles of varying size on the friction-wear properties of polymeric friction composites are investigated. Four friction composites were prepared containing (5, 10 Wt.%) micro silica (MS) particles and (5, 10 Wt.%) nano silica (NS) particles. The samples were produced by a conventional procedure for a dry formulation following dry-mixing, pre-forming and hot pressing. Friction and wear characteristics of the specimens against to a disk made of cast iron were studied. Friction coefficient, specific wear rate and hardness of specimens were obtained. Detailed examinations on the worn surface were analyzed using a scanning electron microscope.

Findings

The results of test showed that the inclusion of nano silicon carbide (SiC) powder improved the wear performance significantly. Friction coefficient (μ) of NS samples was higher than the MS samples. Micro-SiC showed poor performance and μ. High wear performance was exhibited in materials containing 5 Wt.% NS and 10 Wt.% NS.

Originality/value

This paper emphasizes the importance of nano-composites in the automotive industry and helps to industrial firms and academicians working on wear of materials.

Details

Industrial Lubrication and Tribology, vol. 68 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 16 January 2007

A. Kalendová and D. Veselý

This paper seeks to synthesize needle‐shaped anticorrosion pigments based on the ferrites of Zn, Ca and Mg for metal protecting paints.

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Abstract

Purpose

This paper seeks to synthesize needle‐shaped anticorrosion pigments based on the ferrites of Zn, Ca and Mg for metal protecting paints.

Design/methodology/approach

Anticorrosion pigments were synthesized from oxides or carbonates at hot temperatures. The following pigments were synthesized: ZnFe2O4, MgFe2O4, CaFe2O4, Mg0.2Zn0.8Fe2O4, and Ca0.2Zn0.8Fe2O4. The prepared pigments were characterized by means of X‐ray diffraction analysis, by measuring the distribution of particle size and by means of scanning electron microscopy. The synthesized anticorrosion pigments were used to formulate epoxy coatings with PVC = 10 per cent for the synthesized pigment and with the PVC/CPVC ratio = 0.3. The coatings were tested for physical‐mechanical properties and in corrosion atmospheres. The corrosion test results were compared with aluminium zinc phosphomolybdate.

Findings

The needle‐shaped particles were identified in the formulated pigments. It was found that all of the synthesized pigments had high anticorrosion efficiency comparable with that of Zn‐Al phosphomolybdate. The needle‐shaped particles markedly contributed to the advancement of the physical‐mechanical properties of epoxy coatings.

Practical implications

The synthesized pigments can be conveniently used in coatings protecting metal bases against corrosion.

Originality/value

The application of the synthesized pigments with the needle‐shaped particles in anticorrosion paints protecting metals presents a new method. The benefit of the application and method of synthesizing anticorrosion pigments is that they do not contain heavy metals and are acceptable for the environment.

Details

Anti-Corrosion Methods and Materials, vol. 54 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

Book part
Publication date: 30 August 2019

Md. Nazmul Ahsan and Jean-Marie Dufour

Statistical inference (estimation and testing) for the stochastic volatility (SV) model Taylor (1982, 1986) is challenging, especially likelihood-based methods which are…

Abstract

Statistical inference (estimation and testing) for the stochastic volatility (SV) model Taylor (1982, 1986) is challenging, especially likelihood-based methods which are difficult to apply due to the presence of latent variables. The existing methods are either computationally costly and/or inefficient. In this paper, we propose computationally simple estimators for the SV model, which are at the same time highly efficient. The proposed class of estimators uses a small number of moment equations derived from an ARMA representation associated with the SV model, along with the possibility of using “winsorization” to improve stability and efficiency. We call these ARMA-SV estimators. Closed-form expressions for ARMA-SV estimators are obtained, and no numerical optimization procedure or choice of initial parameter values is required. The asymptotic distributional theory of the proposed estimators is studied. Due to their computational simplicity, the ARMA-SV estimators allow one to make reliable – even exact – simulation-based inference, through the application of Monte Carlo (MC) test or bootstrap methods. We compare them in a simulation experiment with a wide array of alternative estimation methods, in terms of bias, root mean square error and computation time. In addition to confirming the enormous computational advantage of the proposed estimators, the results show that ARMA-SV estimators match (or exceed) alternative estimators in terms of precision, including the widely used Bayesian estimator. The proposed methods are applied to daily observations on the returns for three major stock prices (Coca-Cola, Walmart, Ford) and the S&P Composite Price Index (2000–2017). The results confirm the presence of stochastic volatility with strong persistence.

Details

Topics in Identification, Limited Dependent Variables, Partial Observability, Experimentation, and Flexible Modeling: Part A
Type: Book
ISBN: 978-1-78973-241-2

Keywords

Article
Publication date: 9 February 2015

Necat Altinkök, Ferit Ficici and Aslan Coban

The purpose of this study is to optimize input parameters of particle size and applied load to determine minimum weight loss and friction coefficient for Al2O3/SiC…

Abstract

Purpose

The purpose of this study is to optimize input parameters of particle size and applied load to determine minimum weight loss and friction coefficient for Al2O3/SiC particles-reinforced hybrid composites by using Taguchi’s design methodology.

Design/methodology/approach

The experimental results demonstrate that the applied size is the major parameter influencing the weight loss for all samples, followed by particle size. The applied load, however, was found to have a negligible effect on the friction coefficient. Moreover, the optimal combination of the testing parameters was predicted. The predicted weight loss and friction coefficient for all the test samples were found to lie close to those of the experimentally observed ones.

Findings

The optimum levels of the control factors to obtain better weight loss and friction coefficient were A8 (particle size, 60 μm) and B1 (applied load, 20 N), respectively. Taguchi’s orthogonal design was developed to predict the quality characteristics (weight loss and friction coefficient) within the selected range of process parameters (particle size and applied load). The results were validated through ANOVA.

Originality/value

Firstly, hybrid MMCs ceramic powders were produced and then mechanical tests and optimization were performed.

Details

Industrial Lubrication and Tribology, vol. 67 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 8 May 2018

Rajeev Kumar, Sanjeev Bhandari, Atul Goyal and Yogesh Kumar Singla

This paper aims to cover all the aspects of development, investigation and analysis phases to evaluate the slurry erosion performance of test coatings. The powders having…

Abstract

Purpose

This paper aims to cover all the aspects of development, investigation and analysis phases to evaluate the slurry erosion performance of test coatings. The powders having composition of Ni-20Al2O3 and Ni-15Al2O3-5TiO2 were deposited on CA6NM grade turbine steel by using high velocity flame spray (HVFS) technique. The characterization of the coatings was done with the help of SEM/EDS and XRD techniques. Various properties such as micro-hardness and bonding strength of the coatings were also evaluated. Thereafter, these coatings were subjected to an indigenously developed high speed slurry erosion tester at different levels of rotational speed, erodent particle size and slurry concentration. The effect of these parameters on the erosion behavior of coatings was also evaluated. The slurry erosion tests and SEM of the eroded surfaces revealed remarkable improvement in slurry erosion resistance of Ni-15Al2O3-5TiO2 coating in comparison with Ni-20Al2O3 coating.

Design/methodology/approach

Two different compositions of HVFS coating were developed onto CA6NM steel. Subsequently, these coatings were evaluated by means of mechanical and microstructural characterization. Further, slurry erosion testing was done to analyze the erosive wear behavior of developed coatings.

Findings

The coatings were successfully developed by HVFS process. Cross-sectional microscopic analysis of sprayed coatings revealed a continuous and defect-free contact between substrate and coating. Ni-15Al2O3-5TiO2 coating showed higher value of bond strength in comparison with Ni-20Al2O3 coating. Under all the testing conditions, Ni-15Al2O3-5TiO2 coatings showed higher resistance to slurry erosion in comparison with Ni-20Al2O3 coatings. Rotational speed, average particle size of erodent and slurry concentration were found to have proportional effect on specific mass loss of coatings. The mixed behavior (brittle as well as ductile) of the material removal mechanism was observed for the coatings.

Originality/value

From the literature review, it was found that researchers have documented the various studies on Ni-Al2O3, Ni-TiO2 and Al2O3-TiO2 coatings. No one has ascertained the synergetic effect of Alumina and Titania on the slurry erosion performance of Nickel-based coating. In view of this, the authors have developed Ni-Al2O3 and Ni-Al2O3-TiO2 coatings, and an attempt has been made to compare their mechanical, microstructural and slurry erosion characteristics.

Details

Industrial Lubrication and Tribology, vol. 70 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 4 May 2020

Essam Mossalam, Nivin M. Ahmed, Eglal M.R. Souaya and Basil El-Sabbagh

The purpose of this research is to study the physical and mechanical properties beside the durability of concrete as well as corrosion resistance of reinforced concrete by…

Abstract

Purpose

The purpose of this research is to study the physical and mechanical properties beside the durability of concrete as well as corrosion resistance of reinforced concrete by replacing Ordinary Portland cement (OPC) with different ratios of silica fume and meta-kaolin and applying two paint formulations to enhance corrosion resistance and mechanical properties. In this work, modified concrete mixes containing pozzolanic materials of industrial wastes such as silica fume (SF) with ratios ranging between (0, 10 and 15%) and calcined raw material such as meta-kaolin (MK) with ratios (0, 3, 5 and 10%), were introduced using water binder ratio (w/b) 0.45 to study their effect on the physico-mechanical properties and durability of concrete as well as corrosion protection performance of reinforced concrete. Two paint formulations containing the same ingredients except that one of them is free from talc (G1) and the other contains talc (G2) were applied on the rebars embedded in these modified mixes. Talc is known to offer high pH to the surrounding media.

Design/methodology/approach

Modified concrete mixes containing the coated reinforced concrete steel with the different paint formulations in presence and absence of talc were tested, and the corrosion behavior was studied using electrochemical impedance spectroscopy (EIS) in 3.5% NaCl, and the concrete mixes were also tested through their compressive strength, chloride permeability, scanning electron microscope/energy dispersive X-ray analysis and bond strength.

Findings

The results revealed that the hardened reinforced concrete mix containing 10% SF with 5% MK with embedded rebars coated with G2 (paint containing talc) was the best concrete system which offers concrete sustainability besides high corrosion protection performance, i.e. presence of talc in the paints combined with the effect of cement blended with SF and MK showed positive effect on the reinforced concrete properties that leads to more durability and workability.

Originality/value

The integrity of using two efficient methods of corrosion protection beside the effect of the different replacements in concrete mixes containing coated reinforced concrete steel with paint formulations free from talc (G1) and others containing talc (G2), which lead to fatal changes in the pH of the surrounding media (i.e. concrete which has high alkaline pH) to achieve good concrete properties aside with convenient paint formulations together.

Details

Pigment & Resin Technology, vol. 50 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 1 December 1957

A method extensively used in the production of optically flat and finely finished surfaces is that of lapping the surface upon a plate using a loose abrasive mixed into a…

Abstract

A method extensively used in the production of optically flat and finely finished surfaces is that of lapping the surface upon a plate using a loose abrasive mixed into a slurry form with a carrying fluid. If the surfaces finished in this way are in continuous or intermittent sliding contact, it is the author's opinion that any abrasives retained in their surfaces will affect surface wear. This paper reported on some exploratory work to indicate the degree of embedment of abrasive in certain materials lapped by hand.

Details

Industrial Lubrication and Tribology, vol. 9 no. 12
Type: Research Article
ISSN: 0036-8792

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