Processing and characterizations of 2%PF/silica sand core–shell composite powders by selective laser sintering with a higher transmittance fiber laser

In this work, SiO2-encapsulated copper particles/PA12 (Cu-SiO2/PA12) composite powders were prepared by electroless composite plating, and the laser sintering behavior was investigated. Results showed that Cu, Cu2O, CuO, and SiO2 (Cu-SiO2) composite particles were plated on the surface of KH550-modified PA12 powders. The Cu-SiO2 particles existed independently on PA12 surface, and the size was around 200 nm. The melting temperature and crystallization temperature of Cu-SiO2/PA12 composite powders were 183∘C and 150∘C. The results indicate that the selective laser sintering (SLS) process involved the contact of Cu-SiO2/PA12 powders, the formation of sintering neck, the growth of sintering neck, and the formation of fused solid. The Cu-SiO2 composite particles uniformly dispersed in the part due to surface tension, and the contact interface was good due to their similar polarity. The Cu-SiO2/PA12 SLS parts had excellent dimensional precision. The tensile strength of the 15[Formula: see text]W-sintered Cu-SiO2/PA12 specimen was 48[Formula: see text]MPa.

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Shaping ceramics through indirect selective laser sintering

Rapid Prototyping Journal ◽

10.1108/rpj-10-2014-0143 ◽

2016 ◽

Vol 22 (3) ◽

pp. 544-558 ◽

Cited By ~ 21

Author(s):

Jan Patrick Deckers ◽

Khuram Shahzad ◽

Ludwig Cardon ◽

Marleen Rombouts ◽

Jozef Vleugels ◽

...

Keyword(s):

Design Methodology ◽

Dispersion Polymerization ◽

Selective Laser Sintering ◽

Laser Sintering ◽

Powder Synthesis ◽

Composite Powders ◽

Content Type ◽

Production Methods ◽

Nylon 12 ◽

Furnace Sintering

Purpose The purpose of this paper is to compare different powder metallurgy (PM) processes to produce ceramic parts through additive manufacturing (AM). This creates the potential to rapidly shape ceramic parts with an almost unlimited shape freedom. In this paper, alumina (Al2O3) parts are produced, as Al2O3 is currently the most commonly used ceramic material for technical applications. Design/methodology/approach Variants of the following PM route, with indirect selective laser sintering (indirect SLS) as the AM shaping step, are explored to produce ceramic parts: powder synthesis, indirect SLS, binder removal and furnace sintering and alternative densification steps. Findings Freeform-shaped Al2O3 parts with densities up to approximately 90 per cent are obtained. Research limitations/implications The resulting Al2O3 parts contain inter-agglomerate pores. To produce higher-quality ceramic parts through indirect SLS, these pores should be avoided or eliminated. Originality/value The research is innovative in many ways. First, composite powders are produced using different powder production methods, such as temperature-induced phase separation and dispersion polymerization. Second, four different binder materials are investigated: polyamide (nylon-12), polystyrene, polypropylene and a carnauba wax – low-density polyethylene combination. Further, to produce ceramic parts with increased density, the following densification techniques are investigated as additional steps of the PM process: laser remelting, isostatic pressing and infiltration.

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Processing-Structure-Property Relations of Polymer-Polymer Composites Formed by Cryogenic Mechanical Alloying for Selective Laser Sintering Applications

MRS Proceedings ◽

10.1557/proc-625-75 ◽

2000 ◽

Vol 625 ◽

Cited By ~ 2

Author(s):

J. P. Schultz ◽

J. P. Martin ◽

R. G. Kander ◽

C. T. A. Suchicital

Keyword(s):

Mechanical Alloying ◽

Polymer Composites ◽

Effective Means ◽

Selective Laser Sintering ◽

Domain Size ◽

Laser Sintering ◽

Charge Ratio ◽

Composite Particles ◽

Structure Property ◽

Composite Powders

AbstractCryogenic mechanical alloying (CMA) has been shown to be an effective means for producing composite powders for selective laser sintering (SLS). Unlike composite particles made by a coating process, both phases are continuous throughout the particles formed by CMA. Consolidation of these composite particles via SLS offers the possibility of forming parts with a co-continuous microstructure. In this research, the microstructure of mechanically alloyed polymer-polymer composites for use in the SLS process is investigated using transmission electron microscopy. By varying the charge ratio and milling time of the CMA process, the phase domain size of the resulting composite powder can be manipulated. This ongoing work explores the microstructural evolution as the composite powders are consolidated via SLS into macroscopic parts, as well as the relationships between microstructure and bulk properties.

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Processing and Characterization of Core-Shell PA12/Silica Composites Produced by Selective Laser Sintering

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.160-162.756 ◽

2010 ◽

Vol 160-162 ◽

pp. 756-761 ◽

Cited By ~ 2

Author(s):

Jian Hong Wang ◽

Pei Kang Bai ◽

Zhen Lin Zhang ◽

Yu Xin Li

Keyword(s):

Emulsion Polymerization ◽

Silica Particle ◽

Selective Laser Sintering ◽

Laser Sintering ◽

Silica Particles ◽

Sintering Behavior ◽

Core Shell ◽

Dense Structure ◽

Maximum Value

Silica particles coated with PA12 by emulsion polymerization were used as fillers to reinforce PA12 based composites prepared by selective laser sintering (SLS). The influences of the treated and untreated particles on the sintering behavior and mechanical properties of the laser sintered specimens were investigated. It was found that there were many uneven holes in the untreated composites. However, for the treated composites, due to the silica particle surfaces treated by emulsion polymerization, the absorbance of laser was improved and the particles dispersed well in the polymer matrix; a full dense structure was obtained and the properties were enhanced, such as the tend strength increased 30%, the maximum value was 34MPa; the tensile strength increased up to 125%, the maximum value was 44.2 MPa, comparing to the unfilled PA12. Drawing from the results, it can be confirmed that a full dense structure can be obtained and the PA12 matrix was strengthened and toughened when the silica particles were coated with PA12 by emulsion polymerization.

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Process prediction of selective laser sintering based on heat transfer analysis for polyamide composite powders

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2017.12.045 ◽

2018 ◽

Vol 120 ◽

pp. 379-386 ◽

Cited By ~ 14

Author(s):

Xiaoyong Tian ◽

Gang Peng ◽

Mengxue Yan ◽

Shunwen He ◽

Ruijuan Yao

Keyword(s):

Heat Transfer ◽

Selective Laser Sintering ◽

Laser Sintering ◽

Heat Transfer Analysis ◽

Composite Powders ◽

Process Prediction

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Selective Laser Sintering of Porous Silica Enabled by Carbon Additive

10.20944/preprints201710.0003.v1 ◽

2017 ◽

Author(s):

Shuai Chang ◽

Liqun Li ◽

Li Lu ◽

Jerry Y.H. Fuh

Keyword(s):

Fiber Laser ◽

Porous Ceramic ◽

Selective Laser Sintering ◽

Three Dimensional ◽

Porous Silica ◽

Porous Ceramics ◽

Laser Sintering ◽

Freeform Fabrication ◽

Three Dimensional Objects ◽

Controlled Porosity

The aim of this study was to investigate the possibility of a freeform fabrication of porous ceramic parts through selective laser sintering (SLS). SLS was proposed to manufacture ceramic green parts because this additive manufacturing technique can be used to fabricate three-dimensional objects directly without a mold, and the technique has the capability of generating porous ceramics with controlled porosity. However, ceramic printing has yet fully achieved its 3D fabrication capabilities without using polymer binder. Except for the limitation of high melting point, brittleness and low thermal shock resistance from instinct ceramic material properties, the key hurdle lies on very poor absorptivity of oxide ceramics to fiber laser which is widely installed in the commercial SLS equipment. An alternative solution to overcome the poor laser absorptivity via improving material compositions was presented in this study. The positive effect of carbon additive on the absorptivity of silica powder to fiber laser will be discussed. To investigate the capabilities of the SLS process, 3D porous silica structures were successfully prepared and characterized.

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