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Article
Publication date: 1 June 1983

S.M. El‐Sawy, I.M. Morsi and F.A. Abdel‐Mohdy

Three different methods have been studied to prepare silver powder pigments in order to find out the most suitable product for application in conductive paints. X‐ray…

Abstract

Three different methods have been studied to prepare silver powder pigments in order to find out the most suitable product for application in conductive paints. X‐ray analysis, specific gravity, pH value, water solubility, oil absorption, particle size distribution, and particle shape of the prepared silver powders were measured and compared with a commercial pigment. It was found that two of the three grades of silver powders have more suitable properties for application as conductive pigments.

Details

Pigment & Resin Technology, vol. 12 no. 6
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 1 December 2003

M. Umiński and L.M. Saija

A comparison of the difference in chemical nature of re‐dispersible polymer powders useful for the modification of cement based compositions is made. Core‐shell acrylic…

Abstract

A comparison of the difference in chemical nature of re‐dispersible polymer powders useful for the modification of cement based compositions is made. Core‐shell acrylic lattices synthesised by multi‐step sequential polymerisation are formulated and spray‐dried to obtain re‐dispersible powders. The heterogeneous acrylic copolymers prepared are characterised by excellent re‐dispersibility, high chemical stability and good application properties.

Details

Pigment & Resin Technology, vol. 32 no. 6
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 4 February 2021

Junchao Li, Ran Yan, Yanan Yang and Feng Xie

The purpose of this study was to prepare water-based binders, which aimed to avoid printhead blockage and to improve dimensional accuracy of inkjet 3D printing (3DP…

Abstract

Purpose

The purpose of this study was to prepare water-based binders, which aimed to avoid printhead blockage and to improve dimensional accuracy of inkjet 3D printing (3DP) technology, and a feasible algorithm of full-color printing was realized.

Design/methodology/approach

A self-developed color 3D printer was made by using a piezoelectric printhead of Epson Dx-5. Several water-based binders and corresponding gypsum composite powders were prepared, and the optimum binder-powder assembly was then determined through elementary adhesive testing and roller paving testing. Full-color printing was implemented based on halftoning algorithms that used different threshold matrices for different ink channels, and the performances of various algorithms were evaluated in terms of both subjective and objective indices.

Findings

The optimum binder-powder assembly can solve the jamming problem of printhead and realize agreeable dimensional accuracy with the relative error less than 2.5% owing to the satisfying boundary diffusion control ability. And the determined halftone algorithm was verified to be agreeable for 3D color printing.

Originality/value

The prepared approach of water-based binders and gypsum composite powders can be applied to similar 3DP systems even if different materials are introduced. And the used halftone algorithms provide feasible guidelines to the implementation of 3D full-color printing.

Details

Rapid Prototyping Journal, vol. 27 no. 3
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 28 March 2008

K.M. Fan, W.L. Cheung and I. Gibson

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

Abstract

Purpose

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

Design/methodology/approach

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.

Findings

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.

Research limitations/implications

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.

Practical implications

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

Originality/value

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

Details

Rapid Prototyping Journal, vol. 14 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 14 January 2014

Djamila Olivier, Salvador Borros and Guillermo Reyes

A structured customer-driven and integrative methodology to develop materials is described. The proposed methodology is aimed to drive analysis and prioritization of the…

Abstract

Purpose

A structured customer-driven and integrative methodology to develop materials is described. The proposed methodology is aimed to drive analysis and prioritization of the multiple variables involved in a new application case for 3D printing, which involves the development of a new alumina-starch-based powder.

Design/methodology/approach

The development of new powder mixture designed for 3D printing of refractory supports for metal casting moulds is presented. The quality function deployment (QFD) method was applied. Inputs for QFD analysis were found using total quality management tools. Using this approach, six process and material variables were considered to drive a prioritization analysis using a Plackett-Burman Design of Experiment (DOE) array. As performance parameter, compressive resistance was measured and assessed.

Findings

QFD analysis delivered standardized procedures, irrelevant factors and target values for intermediate step parameters. Sintering parameters were found to be the most influencing over compressive resistance.

Research limitations/implications

The methodology was based upon a materials development case for 3D printing.

Practical implications

Knowing in advance the influence of every affecting factor of the process provides a closer control on variability of final part properties, which is a key issue to launch parts into industrial applications. Quality planning and documentation in advanced is the basis for all the quality system of the new additive manufacturing (AM) process to be created.

Originality/value

Procedures for quality planning and control were proposed. This study, as methodological research, intends to introduce industrial engineering practices and quality management routines for AM material/process developers.

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Article
Publication date: 30 March 2020

Gurminder Singh and Pulak Mohan Pandey

The purpose of this study is to study the mechanical, tribological and electrical properties of the copper-graphene (Cu-Gn) composites fabricated by a novel rapid tooling…

Abstract

Purpose

The purpose of this study is to study the mechanical, tribological and electrical properties of the copper-graphene (Cu-Gn) composites fabricated by a novel rapid tooling technique consist of three-dimensional printing and ultrasonic-assisted pressureless sintering (UAPS).

Design/methodology/approach

Four different Cu-Gn compositions with 0.25, 0.5, 1 and 1.5 per cent of graphene were fabricated using an amalgamation of three-dimensional printing and UAPS. The polymer 3d printed parts were used to prepare mould cavity and later the UAPS process was used to sinter Cu-Gn powder to acquire free-form shape. The density, hardness, wear rate, coefficient of friction and electrical conductivity were evaluated for the different compositions of graphene and compared with the pure copper. Besides, the comparison was performed with the conventional method.

Findings

Cu-Gn composites revealed excellent wear properties due to higher hardness, and the lubrication provided by the graphene. The electrical conductivity of the fabricated Cu-Gn composites started increasing initially but decreased afterwards with increasing the content of graphene. The UAPS fabricated composites outperformed the conventional method manufactured samples with better properties such as density, hardness, wear rate, coefficient of friction and electrical conductivity due to homogeneous mixing of metal particles and graphene.

Originality/value

The fabrication of Cu-Gn composite freeform shapes was found to be difficult using conventional methods. The novel technique using a combination of polymer three-dimensional printing and UAPS as rapid tooling was introduced for the fabrication of freeform shapes of Cu-Gn composites and mechanical, tribological and electrical properties were studied. The method can be used to fabricate optimized complex Cu-Gn structures with improved wear and electrical applications.

Details

Rapid Prototyping Journal, vol. 26 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 25 September 2009

C.Z. Yan, Y.S. Shi, J.S. Yang and J.H. Liu

The purpose of this paper is to report a new method, the dissolution‐precipitation process, to prepare nylon‐coated metal powders for the indirect selective laser…

Abstract

Purpose

The purpose of this paper is to report a new method, the dissolution‐precipitation process, to prepare nylon‐coated metal powders for the indirect selective laser sintering (SLS) process.

Design/methodology/approach

The nylon‐12 coated carbon steel powders were prepared by the dissolution‐precipitation process. The powder characteristics are examined by scanning electron microscope (SEM) and laser diffraction particle size analysis. The effect of the applied laser energy density on the three‐point bend strength and dimensional accuracy of the SLS specimens are studied. The influence of nylon‐12 content on the bend strength are also investigated.

Findings

The SEM and laser diffraction particle size analysis results indicate that the steel particles are well coated by nylon‐12 resin. The bend strength of the SLS specimens increases with increasing the applied energy density until it reaches a maximum value, and then further increasing energy density will cause the decrease in the bend strength. The bend strength of the SLS specimens increases with increasing the nylon‐12 content over the investigated range. The dimensional errors in the XY‐and Z‐directions are all increased with the increase in energy density.

Research limitations/implications

This paper only concerns the preparation and SLS of the coated powders. Further investigations are planned into post‐processing, such as binder decomposition and high‐temperature sintering, of the green parts made from the coated powders.

Originality/value

This paper provides a useful method for preparing nylon‐coated metal powders for making metal parts by the indirect SLS process.

Details

Rapid Prototyping Journal, vol. 15 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 1 October 2018

Yunsong Shi, Wei Zhu, Chunze Yan, Jinsong Yang and Zhidao Xia

This study aims to report the preparation, selective laser sintering (SLS) processing and properties of a new nylon elastomer powder. The effects of solvent, dissolution…

Abstract

Purpose

This study aims to report the preparation, selective laser sintering (SLS) processing and properties of a new nylon elastomer powder. The effects of solvent, dissolution temperature and time and cooling method and speed on the particle size and morphologies of the prepared nylon elastomer powder are investigated.

Design/methodology/approach

The prepared nylon elastomer power possesses the particle size of around 50 mm and is spherical in shape, indicating that this study provides the feasible dissolution-precipitation process, a distillation cooling method and a suitable solvent to prepare nylon elastomer powders.

Findings

Compared to pure nylon 12, the nylon elastomer has a lower part bed temperature and a wider sintering window for the SLS process. The wider sintering window indicates the better SLS processibility. The lower part bed temperature is beneficial to the recycling of material and the decrease in the requirement of SLS equipment.

Originality/value

The nylon elastomer in this study has a lower part bed temperature and a wider sintering window for the SLS process. The wider sintering window indicates better SLS processibility. The lower part bed temperature is beneficial to the recycling of material and the decrease in the requirement of SLS equipment.

Details

Rapid Prototyping Journal, vol. 24 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 26 July 2021

Yi Fu, Chunze Yan, Xiao Yang, Zhufeng Liu, Peng Chen and Zhaoqing Li

The purpose of this paper is to prepare metal/polymer composite materials prepared by additive manufacturing (AM) technology.

Abstract

Purpose

The purpose of this paper is to prepare metal/polymer composite materials prepared by additive manufacturing (AM) technology.

Design/methodology/approach

The effect of sintering parameters including laser power, scanning speed and slice thickness on strength and accuracy of selective laser sintering (SLS) parts were analyzed experimentally. Then, the laser sintering mechanism of nylon-12 coated copper was discussed through analyzing the interfacial reaction of nylon-12 and copper. The SLS parts were infiltrated with epoxy resin to meet the strength requirements of injection molding.

Findings

In this study, mechanical mixed nylon-12/copper and nylon-12 coated copper composite powders were investigated and compared as SLS materials. An effective dissolution–precipitation method was proposed to prepare nylon-12 coated copper powders with better processing and mechanical properties. The bending strength and modulus of fabricated parts after infiltration with epoxy reach 65.3 MPa and 3,200 MPa, respectively.

Originality/value

The composite materials can be used in the manufacture of injection molds with a conformal cooling channel for the production of common plastics in prototype quantities, showing a broad application prospect in rapid tooling.

Details

Rapid Prototyping Journal, vol. 27 no. 7
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 June 2000

B. Engel and D.L. Bourell

Selective laser sintering (SLS) is a solid freeform fabrication process whereby a part is built layerwise by scanning a powder bed. The processability of metal powder

Abstract

Selective laser sintering (SLS) is a solid freeform fabrication process whereby a part is built layerwise by scanning a powder bed. The processability of metal powder varies depending on the state of the powder prior to SLS. A powder thermal pre‐treatment was developed which involved degassing the powder at an elevated temperature in a vacuum. Without powder thermal pre‐treatment, the powder may flow poorly and may “ball” or form molten clumps during the laser exposure rather than wetting into the present and previous layer. These effects result in SLS parts with poor surface finish, mechanical properties and density. The purpose of this study was to identify for titanium alloy powder the mechanisms responsible for the improvements obtained after powder thermal pre‐treatment and to optimize the thermal excursion.

Details

Rapid Prototyping Journal, vol. 6 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

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