Research of Post-Treatment Effect on Structure of Alloys Manufactured Using Additive Technologies

The effect of cold isostatic pressing of EP648 alloy after selective laser sintering is researched. The effect of cold isostatic pressing on the porosity of the structure of a material manufactured by additive technologies (AT) has been established. It is proposed to consider cold isostatic pressing as a method of subsequent treatment of products ("post-treatment") made by selective laser sintering.

Quasi-Static and Dynamic Mechanical Properties of a Ti-6Al-4V Titanium Alloy Produced Using Unconventional Manufacturing Methods

The purpose of this paper was to determine the mechanical properties of a Ti-6Al-4V titanium alloy produced by traditional CIP (Cold Isostatic Pressing) and by LENS (Laser Engineered Net Shaping), an additive manufacturing process. A reference material, being a commercial Ti-6Al-4V alloy, was also tested. The strength test specimens were produced from a high-quality, Grade 5 titanium powder. Each specimen had its density, porosity, and hardness determined. Compression curves were plotted for the tested materials from the strength test results with static and dynamic loads. These tests were performed on an UTS (Universal Testing Machine) and an SHPB (Split Hopkinson Pressure Bar) stand. The test results obtained led to the conclusion that the titanium alloy produced by CIP had lower strength performance parameters than its commercially-sourced counterpart. The LENS-produced specimens outperformed the commercially-sourced alloy both in static and dynamic load conditions.

High-Density Ceramics Obtained By Andesite Basalt Sintering

Modern industrial requirements include not only the usage of constructive materials with good mechanical properties but also materials obtained through environmentally friendly and low-cost processing procedures. Basalt, as a low-cost raw material, is regarded as a good candidate for industrial constructive parts production. In the present study, andesite basalt originated from the deposit site "Donje Jarinje", Serbia, was examined as a potential raw material for high-density ceramics production. The production of high-density ceramics included dry milling, homogenization, cold isostatic pressing, and sintering in the air. To determine the optimal processing parameters the sintering was conducted at 1040, 1050, 1060, 1070, and 1080 °C, and afterward the sintering duration was varied from 30 to 240 min at the optimal sintering temperature of 1060 °C. Characterization of the starting and sintered materials included the estimation of particle size distribution, density, hardness, and fracture toughness complemented with X-ray diffraction, light optical microscopy, scanning electron microscopy, and energy dispersive spectroscopy analysis. Phase transformations did not occur during processing in the investigated temperature range from 1040 to 1080 °C. The obtained research results showed that 99.5% of relative density and the highest hardness and fracture toughness values of 6.7 GPa and 2.2 MPaÖm, respectively, were achieved for the andesite basalt sintered at 1060 °C for 60 min in the air. The results of the presented study confirmed that the sintered andesite basalt can be used as a high-density ceramic material for various industrial applications since this environmentally friendly material shows satisfactory mechanical properties.

Ionic and Thermal Transport in Na-Ion-Conducting Ceramic Electrolytes

We have studied the ionic and thermal transport properties along with the thermodynamic key properties of a Na-ion-conducting phosphate ceramic. The system Na1+xAlxTi2−x(PO4)3 (NATP) with x = 0.3 was taken as a NASICON-structured model system which is a candidate material for solid electrolytes in post-Li energy storage. The commercially available powder (NEI Coorp., USA) was consolidated using cold isostatic pressing before sintering. In order to compare NATP with the “classical” NASICON system, Na1+xZr2(SiO4)x(PO4)3−x (NaZSiP) was synthesized with compositions of x = 1.7 and x = 2, respectively, and characterized with regard to their ionic and thermal transport behavior. While ionic conductivity of the NaZSiP compositions was about more than two orders of magnitude higher than in NATP, the thermal conductivity of the NASICON compound showed an opposite behavior. The room temperature value was about a factor two higher in NATP compared to NaZSiP. While the thermal conductivity decreases with increasing temperature in NATP, it increases with increasing temperature in NaZSiP. However, the overall change of this thermal transport parameter over the measured temperature range from room temperature up to 800 °C appeared to be relatively small.

Testing of Sinters Made of Copper Powders Coated with Carbon Structure Containing Graphene

This paper presents the results of preliminary tests on specimens made from mixtures of dendritic copper powder (CuE) with the graphene-coated copper powder (CuG) in a range from 20% to 100% (CuG). The properties of the powder mixtures, green compacts and sinters were determined. To study the properties of the powder mixtures, the following tests were carried out: a measurement of the CuG powder grain size after the grinding process, measurements of the bulk density and tap density of the prepared powder mixtures. The porosity of the produced green compacts and the sinters was calculated as well as the densification capabilities of the powder mixtures by die pressing, cold isostatic pressing and sintering in a reducing atmosphere were tested. Moreover, the nature of the porosity formation was analysed using an optical microscope and the Brinell hardness was determined. The measured Brinell hardness was in the range of 17 HB for sinters made from CuG to 34 HB for sinters made from a 20% CuG powder mixture. More than six hundred measurements that were made in this study show that the high CuG content in the powder mixture reduce the hardness of the sinters as well increase their porosity.