Porosity analysis of superfine-grain graphite IG-110 and ultrafine-grain graphite T220

The aim of this study was to synthesize, characterize, and evaluate degradation and biocompatibility of poly(lactic-co-glycolic acid) + hydroxyapatite / β-tricalcium phosphate (PLGA+HA/βTCP) scaffolds incorporating simvastatin (SIM) to verify if this biomaterial might be promising for bone tissue engineering. Samples were obtained by the solvent evaporation technique. Biphasic ceramic particles (70% HA, 30% βTCP) were added to PLGA in a ratio of 1:1. Samples with SIM received 1% (m:m) of this medication. Scaffolds were synthesized in a cylindric-shape and sterilized by ethylene oxide. For degradation analysis, samples were immersed in PBS at 37 °C under constant stirring for 7, 14, 21, and 28 days. Non-degraded samples were taken as reference. Mass variation, scanning electron microscopy, porosity analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetry were performed to evaluate physico-chemical properties. Wettability and cytotoxicity tests were conducted to evaluate the biocompatibility. Microscopic images revealed the presence of macro, meso, and micropores in the polymer structure with HA/βTCP particles homogeneously dispersed. Chemical and thermal analyses presented very similar results for both PLGA+HA/βTCP and PLGA+HA/βTCP+SIM. The incorporation of simvastatin improved the hydrophilicity of scaffolds. Additionally, PLGA+HA/βTCP and PLGA+HA/βTCP+SIM scaffolds were biocompatible for osteoblasts and mesenchymal stem cells. In summary, PLGA+HA/βTCP scaffolds incorporating simvastatin presented adequate structural, chemical, thermal, and biological properties for bone tissue engineering.

Download Full-text

Relative Grain Boundary Energies in Ultrafine Grain Ni Obtained by High Pressure Torsion

SSRN Electronic Journal ◽

10.2139/ssrn.3539158 ◽

2020 ◽

Author(s):

J. Zimmerman ◽

A. Sharma ◽

Eugen Rabkin ◽

S.V. Divinsk

Keyword(s):

High Pressure ◽

Grain Boundary ◽

High Pressure Torsion ◽

Ultrafine Grain

Download Full-text

Study on strong spinning preparation method and mechanism of the industrial pure titanium ultrafine crystallization

Journal of Engineered Fibers and Fabrics ◽

10.1177/1558925019895256 ◽

2019 ◽

Vol 14 ◽

pp. 155892501989525

Author(s):

Yu Yang ◽

Yanyan Jia

Keyword(s):

Heat Treatment ◽

High Performance ◽

Pure Titanium ◽

Grain Structure ◽

Theoretical Research ◽

Ultrafine Grain ◽

Forming Process ◽

Spinning Process ◽

And Performance ◽

Material Utilization

Ultrafine crystallization of industrial pure titanium allowed for higher tensile strength, corrosion resistance, and thermal stability and is therefore widely used in medical instrumentation, aerospace, and passenger vehicle manufacturing. However, the ultrafine crystallizing batch preparation of tubular industrial pure titanium is limited by the development of the spinning process and has remained at the theoretical research stage. In this article, the tubular TA2 industrial pure titanium was taken as the research object, and the ultrafine crystal forming process based on “5-pass strong spin-heat treatment-3 pass-spreading-heat treatment” was proposed. Based on the spinning process test, the ultimate thinning rate of the method is explored and the evolution of the surface microstructure was analyzed by metallographic microscope. The research suggests that the multi-pass, medium–small, and thinning amount of spinning causes the grain structure to be elongated in the axial and tangential directions, and then refined, and the axial fiber uniformity is improved. The research results have certain scientific significance for reducing the consumption of high-performance metals improving material utilization and performance, which also promote the development of ultrafine-grain metals’ preparation technology.

Download Full-text

Automated inclusion and porosity analysis of metal additive manufacturing parts

Microscopy and Microanalysis ◽

10.1017/s1431927621010230 ◽

2021 ◽

Vol 27 (S1) ◽

pp. 2936-2936

Author(s):

Petrus Pistorius

Keyword(s):

Additive Manufacturing ◽

Metal Additive Manufacturing ◽

Porosity Analysis ◽

Metal Additive

Download Full-text

Porosity Analysis of Additive Manufactured Parts Using CAQ Technology

Materials ◽

10.3390/ma14051142 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1142

Author(s):

Peter Pokorný ◽

Štefan Václav ◽

Jana Petru ◽

Michaela Kritikos

Keyword(s):

Manufacturing Process ◽

Scanning Speed ◽

Additive Technologies ◽

Integration Time ◽

Detector Resolution ◽

Porosity Analysis ◽

3D Scans ◽

Printing Direction ◽

Non Destructive

Components produced by additive technology are implemented in various spheres of industry, such as automotive or aerospace. This manufacturing process can lead to making highly optimized parts. There is not enough information about the quality of the parts produced by additive technologies, especially those made from metal powder. The research in this article deals with the porosity of components produced by additive technologies. The components used for the research were manufactured by the selective laser melting (SLM) method. The shape of these components is the same as the shape used for the tensile test. The investigated parts were printed with orientation in two directions, Z and XZ with respect to the machine platform. The printing strategy was “stripe”. The material used for printing of the parts was SS 316L-0407. The printing parameters were laser power of 200 W, scanning speed of 650 mm/s, and the thickness of the layer was 50 µm. A non-destructive method was used for the components’ porosity evaluation. The scanning was performed by CT machine METROTOM 1500. The radiation parameters used for getting 3D scans were voltage 180 kV, current 900 µA, detector resolution 1024 × 1024 px, voxel size 119.43 µm, number of projections 1050, and integration time 2000 ms. This entire measurement process responds to the computer aided quality (CAQ) technology. VG studio MAX 3.0 software was used to evaluate the obtained data. The porosity of the parts with Z and XZ orientation was also evaluated for parts’ thicknesses of 1, 2, and 3 mm, respectively. It has been proven by this experimental investigation that the printing direction of the part in the additive manufacturing process under question affects its porosity.

Download Full-text

Facile route to bulk ultrafine-grain steels for high strength and ductility

Nature ◽

10.1038/s41586-021-03246-3 ◽

2021 ◽

Vol 590 (7845) ◽

pp. 262-267

Author(s):

Junheng Gao ◽

Suihe Jiang ◽

Huairuo Zhang ◽

Yuhe Huang ◽

Dikai Guan ◽

...

Keyword(s):

High Strength ◽

Ultrafine Grain ◽

Strength And Ductility ◽

Facile Route

Download Full-text

Fracture and Fatigue Resistance of Ultrafine Grain CuCrZr Alloy Produced ECAP

Materials Science Forum ◽

10.4028/www.scientific.net/msf.503-504.811 ◽

2006 ◽

Vol 503-504 ◽

pp. 811-816 ◽

Cited By ~ 12

Author(s):

Alexei Vinogradov ◽

Kazuo Kitagawa ◽

V.I. Kopylov

Keyword(s):

Growth Rate ◽

Crack Growth Rate ◽

Crack Growth ◽

Stable Crack Growth ◽

Ultrafine Grain ◽

J Integral ◽

Present Communication ◽

Angular Pressing ◽

Fatigue And Fracture ◽

Anisotropy Of Mechanical Properties

Anisotropy of mechanical properties, fatigue and fracture resistance of precipitation hardened CuCrZr alloy ultrafine (UFG) grained by equal-channel angular pressing (ECAP) is in focus of the present communication. Fracture toughness was estimated in terms of J-integral and the fatigue crack growth rate was quantified. It was found that although the estimated JIC-value appeared lower than that reported in the literature for a reference alloy, the ductility, fracture and crack growth resistance remained satisfactory after ECAP while the tensile strength and fatigue limit improved considerably. The stable crack growth rate did not differ very much for ECAP and reference conventional CuCrZr and no remarkable anisotropy in the stable crack growth was noticed.

Download Full-text