Texturing and Phase Evolution in Ti-6Al-4V: Effect of Electron Beam Melting Process, Powder Re-Using, and HIP Treatment

The research demonstrates microstructural changes and development of specific texture in Ti-6Al-4V specimens produced by electron beam melting (EBM) under different conditions. The effect of two factors, namely, raw material (powder) recycling and hot isostatic pressing (HIP), on the EBM produced samples structure and properties, has been explored. The as-printed and treated samples were investigated using electron backscattered diffraction (EBSD) analysis. Modification of mechanical properties after the EBM and HIP are explained by the EBSD data on microstructural phenomena and phase transformations. The work is devoted to assessing the possibility of reusing the residual titanium alloy powder for the manufacture of titanium components by the combination of EBM and HIP methods.

Investigasi mekanisme korosi pada pipa pemanas udara di Pabrik Gula Pagotan Madiun

This study aims to determine the inner surface morphology of pipes and to identify pipe corrosion products using stereo microsocope and X-ray diffraction (XRD) observations. In this study, the sample used was a piece of Blacksteel gas pipe that had been used for 107 days and 570 days with dimensions of 3 cm in length and 4 cm in diameter. The sample was taken from the Air heater Unit of the Pagotan Madiun sugar factory, East Java, Indonesia. Morphology the inside of the tube was observed with a CARL ZEISS Stemi DV4 stereo microscope (32x magnification). Furthermore, the rust material powder on the sample pipe was taken to determine the corrosion product using the XRD X'Pert PRO instrument. The results of observation by using a stereo microscope on the inner surface of air heater pipe that had been used for 107 days and 570 days indicated that the pipe surface experienced corrosion and peeling. From the results of X-ray diffraction (XRD) observations, FeOOH layer were formed from Fe2+ and OH- ions produced from O2 and H2O molecules in the smoke gas from burning bagasse. At the bottom of FeOOH layer, Fe3O4 was formed from the subsequent reaction between FeOOH and Fe2+ ions.Keywords: pipe, air heater, corrosion, smoke gas.

Pengaruh Kecepatan Pengadukan pada Proses Stircasting terhadap Sifat Mekanik pada Paduan Aluminium

<p class="Abstract">The composite material is a material composed of a mixture or combination of two or more of the major elements that macro differ in shape and material composition that basically can not be separated. In this research, the aluminum used was the outcome of production cesspool with the addition of volcanic dust from Mount Kelud by 2% as reinforcement. The stir casting process is the casting process by adding a material (powder form) in pure metal (aluminum), which has been melted and then stirring constantly. After that, the composite materials (the volcanic dust from Mount Kelud) were mixed slowly into the stirred liquid material. In this research, the variations of stirring speed were 0,200,300,400,500 and 600 rpm. The stirring each time for 4 minutes. In this study, the stirring speed in the casting process was 0, 200, 300, 400, 500, and 600 rpm. Tensile test, Impact test, and microstructure observations were carried out on the casting results. From these tests, the highest modulus of elasticity and impact value was obtained at the 600rpm stirring process. It may due to globular grains are more evenly distributed. And the result of metallographic testing was stirring speed could affect the amount and density of composite grain structure. The faster the stirring, the grain structure was getting smaller and close.</p>

Effect of peanut and walnut shells powders on tensile properties and morphological test by using heat cured PMMA as a matrix for prosthetic Denture

In the current Research , the heat cured matrix material powder of PMMA was reinforced with peanut and walnut shells (natural powders) which are chemically treated with 5% (w/v) (NaOH) to improve the matrix bonding (PMMA) before being used as a reinforcing powder and adding to exactly similar averages particle sizes ≤ (53µm), with different weight fractions of (4, 8, and 12 wt.%). The ASTM D638 is used for composite specimens of the tensile test. The results indicated that the Elastic modulus values reached its maximum value at (8 wt.%.) when reinforced with peanut shells particles (1.053Gpa) , while ,the values of tensile strength, elongation percentage at break, decrease as the weight fraction of peanut and walnut shells powder increase and the lowest values is obtained by reinforcing with peanut shells particles to reach their minimum values at (12 wt.%.) where the lowest values of them are (29 MPa, 2.758% ) respectively. The fracture surface morphology of pure PMMA seemed to be homogenous morphology in (SEM) test, whereas the fracture surface morphology of PMMA composite reinforced by (peanut and walnut shells) powders and shows a roughness fracture surface morphology this refer to semi ductile to ductile materials.

Study on the Influence of the New Type of Powder Metallurgy Ti-Al-Nb Alloy Hot Press Sintering Process on the Microstructure

Based on the hot-pressing sintering process, the kinetics of hot-pressing sintering crystal grain growth and the hot-pressing sintering densification kinetics, the mixing ratio of the raw material powder and the hot-pressing sintering system are designed. The pressure is maintained at 30 MPa from the temperature rise to the end of the sintering process, and wait until the temperature reaches the corresponding hot pressing sintering temperature (1200°C~1400°C), keep the corresponding time for 1.5h~4.5h, stop heating and depressurize, and the alloy billet is cooled to room temperature with the furnace. The main phases of Ti2AlNb powder and hot pressing sintering process are TiAl and Ti3Al.

Manufacture of Cellular Glass Using Oak Leaves as a Foaming Vegetable Agent

The manufacture experimentation of a cellular glass exclusively from mineral waste and natural residues using the unconventional technique of microwave irradiation was the objective of the research whose results are presented in the paper. The originality of the paper results from the use of oak leaves as a vegetable foaming agent as well as the use of microwave energy in heating processes of the raw material powder mixture for manufacturing thermal insulating materials for the building construction. Worldwide, these processes use only conventional heating techniques. The experimental results led to the conclusion that both the use of waste and residues, as well as the unconventional heating technique allow to obtain porous materials with structural homogeneity having apparent densities and thermal conductivities that can decrease up to 0.34 g/cm3, and 0.071 W/m·K respectively. The compressive strength corresponding to the materials with the lowest values of density and thermal conductivity has an acceptable value (1.2 MPa) for the field of application. The specific energy consumption is around 1 kWh/kg, being approximately at the same level with the values of industrial consumptions achieved by conventional techniques.

Improving the recipe and technology of wheat bread with apple pomace

The effect of apple raw material (powder from apple pomace and frozen apple pomace) on the duration of individual operations of the technological process of the straight method of wheat bread production, such as the kneading duration, the number of punchings, the duration of the dough fermentation and dough pieces proofing, was investigated in the work. As studies showed, when using secondary apple raw materials in wheat bread production, the amount of yeast must be increased to 3-4%, compared to 1-2% introduced to the control sample. When kneading the dough, apple pomace powder is mixed with dry ingredients according to the developed recipes. When preparing the dough, freshly frozen apple pomace must first be soaked in a mixture of vegetable oil and warm water (water temperature is 28-30 ?) with constant stirring and bringing to a homogeneous consistency and the pomace complete defrosting. The degree of influence of products from the secondary apple raw materials on the technological process and bread quality depend on the type and quantity of the product added to the dough (apple powder or frozen apple pomace is used). The amount of water was also increased by replacing part of the premium wheat flour with buckwheat flour and apple pomace powder. While using fresh frozen apple pomace, the amount of water was reduced, the other ingredients in the recipe were not changed. The additives put to the recipe stimulate the dough fermentation process and reduce it. At the same time, the duration of the dough maturation and the proofing operations are reduced. The addition of fresh frozen apple pomace improves the porosity and taste of bread to a greater extent..

Efficacy of invasive alien plants in controlling Arionidae slugs

Aim of study: To develop an alternative slug control method, we explored the use of plant material from seven invasive plant species against Arion slugs.Area of study: The experiments were performed at the University of Ljubljana (Slovenia).Material and methods: In laboratory (exp. A-C) and semi-field studies (exp. D), we investigated the contact and barrier efficacy of plant material (powder or liquid formulation) of seven invasive plant species (Japanese knotweed, bohemian knotweed, Canadian goldenrod, giant goldenrod, staghorn sumac, tree of heaven, and false indigo) against Arion slugs. In order to test a contact efficacy of the substance (exp. A), slugs were rolled in a plant material powder. In exp. B, powder made from a plant material was used as a barrier for slugs. Antifeedant effect of the slugs was tested in exp. C, where lettuce leaves were treated with a liquid formulation of a plant material. In exp. D, all above mentioned techniques were used in a semi-field trial.Main results: The results of our studies showed that the plant material of staghorn sumac, giant goldenrod, and Japanese knotweed showed the strongest anti-feedant and barrier effects against the slugs. In the semi-field trial, only 7% of the plants treated with giant goldenrod plant material were attacked by slugs.Research highlights: A contact efficacy of plant powders against Arion slugs was not confirmed in our investigation. Furthermore, several plant powders (goldenrods, staghorn sumac) showed good barrier efficacy. A semi-field trial showed that plant material (giant goldenrod) could represent an alternative solution in slug control.