Effect of the Process Atmosphere Composition on Alloy 718 Produced by Laser Powder Bed Fusion

The detrimental effect of nitrogen and oxygen when it comes to the precipitation of the strengthening γ’’ and γ’ phases in Alloy 718 is well-known from traditional manufacturing. Hence, the influence of the two processing atmospheres, namely argon and nitrogen, during the laser powder bed fusion (L-PBF) of Alloy 718 parts was studied. Regardless of the gas type, considerable losses of both oxygen of about 150 ppm O2 (≈30%) and nitrogen on the level of around 400 ppm N2 (≈25%) were measured in comparison to the feedstock powder. The utilization of nitrogen as processing atmosphere led to a slightly higher nitrogen content in the as-built material—about 50 ppm—compared to the argon atmosphere. The presence of the stable nitrides and Al-rich oxides observed in the as-built material was related to the transfer of these inclusions from the nitrogen atomized powder feedstock to the components. This was confirmed by dedicated analysis of the powder feedstock and supported by thermodynamic and kinetic calculations. Rapid cooling rates were held responsible for the limited nitrogen pick-up. Oxide dissociation during laser–powder interaction, metal vaporization followed by oxidation and spatter generation, and their removal by processing atmosphere are the factors describing an important oxygen loss during L-PBF. In addition, the reduction of the oxygen level in the process atmosphere from 500 to 50 ppm resulted in the reduction in the oxygen level in as-built component by about 5%.

ANALYZING THE RELIGIOUS PRACTICES AMONG THE ELECTRICAL MOTOR INSTALLATION DEPARTMENT STUDENTS IN SMKN 2 PEURELAK ACEH TIMUR

Education is a conscious effort to create a learning process atmosphere which students actively develop their potential. Religious value education is very closely with humans’ character. The aim of the study was to assess the implementation of religious practice in the SMKN 2 Peurelak. The design of the study is kind of Pre-Experimental design with qualitative approach. The experiment class used was an Electrical Motor Installation Department, class X, XI, and XII. However, for the interview needed, the participants involved were four students from different classes and two teachers. The instrument used in the study was a set of the interview protocol. This qualitative method would be analyzed by encoding the respondents’ initials and their transcripts. The transcript will be analyzed by identifying emerging themes. The finding result showed that the students sensed their spirit and motivation were increased after the implementation of religious activities in their school. They asserted feeling calm in heart, more concentrated on studying and well-disciplined between learning and play.

An Innovative Approach on Directed Energy Deposition Optimization: A Study of the Process Environment’s Influence on the Quality of Ti-6Al-4V Samples

Blown powder additive manufacturing technologies are not restricted to the use of a process chamber. This feature allows to build larger components with respect to conventional powder bed processes. This peculiarity is mostly promising for manufacturing large components or repairing/rebuilding parts of large systems. The main downside of using an open environment, even if a protective shielding gas system is adopted, is the lack of control of process atmosphere. This is particularly critical for titanium alloys which are very sensitive to oxygen/nitrogen pick-up; they have a detrimental effect on ductility, by causing embrittlement and possibly leading to the formation of cracks. It is then important to address how environmental factors, such as process atmosphere and platform temperature, impact not only on the processability but also on the final component properties, both from a compositional and mechanical point of view. The correlations between these environmental factors and microstructure, interstitials content, grain size, and hardness were investigated. Moreover, the Hall–Petch equation was then adopted to additive manufacturing microstructures, characterized by a columnar grain morphology, and used to further investigate the relationship intercurring between grains and hardness and how different microstructures might influence this correlation.

Transition from freestanding SnO2 nanowires to laterally aligned nanowires with a simulation-based experimental design

In this study, we used simulations as a guide for experiments in order to switch freestanding nanowire growth to a laterally aligned growth mode. By means of finite element simulations, we determined that a higher volumetric flow and a reduced process pressure will result in a preferred laterally aligned nanowire growth. Furthermore, increasing the volumetric flow leads to a higher species dilution. Based on our numerical results, we were able to successfully grow laterally aligned SnO2 nanowires out of gold film edges and gold nanoparticles on a-plane sapphire substrates. In our experiments a horizontal 2-zone tube furnace was used. The generation of Sn gas was achieved by a carbothermal reduction of SnO2 powder. However, we observed no elongation of the nanowire length with an increase of the process time. Nevertheless, an alternating gas exchange between an inert gas (Ar) and an oxygen-containing process atmosphere yielded an elongation of the laterally aligned nanowires, indicating that the nanowire growth takes place in a transient period of the gas exchange.

METHODS FOR ENSURING LOW HUMIDITY IN THE INTERNAL VOLUME OF CERAMIC-METAL CASES IN SERIES PRODUCTION OF INTEGRATED CIRCUITS

Stricter requirements for reliability of integrated circuits in ceramic-metal packages led to the increased requirements for process and quality control of the atmosphere in which circuits are being sealed. In our experiments we manage to reduce humidity in integrated circuit packages, by the constant monitoring of the sealing process atmosphere.

The Conditions and Results of Ferrite Based on Multicomponent Crystal Formation in High Entropic Oxide Systems

High-entropic magneto-plum-bite structured crystal phases were theoretically calculated and then prepared by solid state synthesis. The compositions and formation conditions for by-product, such as spinel structured multicomponent crystals, that had not been previously described in literature, were analyzed. The list of elements which can be the main components of such phases was defined. Important conclusions about the conditions for growing high-entropy crystals from melts were made. Particularly, it was shown that the obligatoriness for additional oxidation of the melt should be taken into account (relative to the level that the composition of the melt itself and the process atmosphere can provide).