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Steinau an der Straße, Germany

Mroz W.,Military University of Technology | Budner B.,Military University of Technology | Syroka R.,Military University of Technology | Niedzielski K.,University of Lodz | And 4 more authors.
Journal of Biomedical Materials Research - Part B Applied Biomaterials

The use of porous titanium-based implant materials for bone contact has been gaining ground in recent years. Selective laser melting (SLM) is a rapid prototyping method by which porous implants with highly defined external dimensions and internal architecture can be produced. The coating of porous implants produced by SLM with ceramic layers based on calcium phosphate (CaP) remains relatively unexplored, as does the doping of such coatings with magnesium (Mg) to promote bone formation. In this study, Mg-doped coatings of the CaP types octacalcium phosphate and hydroxyapatite (HA) were deposited on such porous implants using the pulsed laser deposition method. The coated implants were subsequently implanted in a rabbit femoral defect model for 6 months. Uncoated implants served as a reference material. Bone-implant contact and bone volume in the region of interest were evaluated by histopathological techniques using a tri-chromatographic Masson-Goldner staining method and by microcomputed tomography (lCT) analysis of the volume of interest in the vicinity of implants. Histopathological analysis revealed that all implant types integrated directly with surrounding bone with ingrowth of newly formed bone into the pores of the implants. Biocompatibility of all implant types was demonstrated by the absence of inflammatory infiltration by mononuclear cells (lymphocytes), neutrophils, and eosinophils. No osteoclastic or foreign body reaction was observed in the vicinity of the implants. lCT analysis revealed a significant increase in bone volume for implants coated with Mg-doped HA compared to uncoated implants. © 2014 WILEY PERIODICALS, INC. Source

Niendorf T.,University of Kassel | Brenne F.,University of Paderborn | Krooss P.,University of Kassel | Krooss P.,TU Bergakademie Freiberg | And 5 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science

In the current study, a Fe-Mn-Al-Ni shape memory alloy is processed by additive manufacturing for the first time. Microstructural evolution upon processing is strongly affected by thermal gradients and solidification velocity and, thus, by processing parameters and the actual specimen geometry. By single-step solutionizing heat treatment pronounced grain growth is initiated leading to microstructures showing good reversibility. The compressive stress–strain response revealed maximum reversible pseudo-elastic strain of about 7.5 pct. Critical steps toward further optimization of additively manufactured Fe-Mn-Al-Ni shape memory alloys are discussed. © 2016 The Minerals, Metals & Materials Society and ASM International Source

Niendorf T.,University of Paderborn | Leuders S.,University of Paderborn | Riemer A.,University of Paderborn | Richard H.A.,University of Paderborn | And 2 more authors.
Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science

For additive manufacturing of metals, selective laser melting can be employed. The microstructure evolution is directly influenced by processing parameters. Employing a high energy laser system, samples made from austenitic stainless steel were manufactured. The microstructure obtained is characterized by an extremely high degree of anisotropy featuring coarse elongated grains and a 〈001a〉 texture alongside the build direction during processing. Eventually, the anisotropy of the microstructure drastically affects the monotonic properties of the current material. © 2013 The Minerals, Metals & Materials Society and ASM International. Source

Niendorf T.,University of Paderborn | Leuders S.,University of Paderborn | Riemer A.,University of Paderborn | Brenne F.,University of Paderborn | And 3 more authors.
Advanced Engineering Materials

In the current study, selective laser melting is employed for direct manufacturing of functionally graded materials. An appropriate set of processing parameters allowing for direct microstructure manipulation of stainless steel is presented. Thorough analyses reveal a steep microstructural gradient resulting in distinct local mechanical properties. The process introduced will further give raise to the rapidly evolving field of additive manufacturing. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Method and apparatus for producing a large three-dimensional work piece. In a method for producing a three-dimensional work piece, a layer of raw material powder is applied onto a carrier (

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