1,721,005 research outputs found
Chemical surface finishing of AlSi10Mg components made by additive manufacturing
No full textOne of the most critical issues of a component realized by Additive Manufacturing is the surface quality. In particular, in case of high levels of roughness, the functionality of the component and its mechanical properties are significantly affected. Chemical finishing offers the advantage of acting on the whole surface, without the need of tools. In this preliminary work several specimen of AlSi10Mg have been treated firstly by Chemical Machining to remove the gross irregularities, followed by Chemical Brightening to further smooth the surface. The results are promising; the surface parameters analyzed indicate that the treatment improves the surface quality. © 2018 Society of Manufacturing Engineers (SME
Finite element modeling of superplastic forming of friction stir processed AZ31B mg alloy
No full textSuperplastic forming (SPF) is considered to be a near net shape manufacturing technique, mainly adopted to realize aircraft and automotive parts, which requires relatively high tooling and assembly costs. Furthermore the tuning of the process is a non trivial operation since very limited reliable models have been developed to predict the complex geometries obtained through SPF. In such context several researches, based on finite element method (FEM,) have been conducted on the numerical optimization of conventional SPF processes. Friction Stir Processing (FSP) can be used combined with conventional SPF to enhance the superplastic material behavior by means of grain refinement treatment locally performed. From this point of view very few models have been developed to simulate the different superplastic behavior distinguishing the materials after the application of FSP. In this work free bulge forming tests of AZ31B Mg alloy was experimentally performed by means of blow forming laboratory-scale equipment as well as FEM analysis were conducted to simulate the SPF in two different cases: unprocessed and friction stir processed (FSProcessed) condition. The most relevant parameters of the constitutive numerical model were optimized by numerical-experimental comparison. More specifically material strength factor (K) and strain rate sensitivity index (m) were considered during the parametric optimization. Strain and thickness distributions were compared to the experimental measurements in order to individuate the optimized constitutive equations governing the superplastic behavior in both case studies
Thermal degradation of pesticides under oxidative conditions
No full textThe paper addresses thermal decomposition under oxidative conditions of 16 pesticides. Within the scope of the paper such 16 substances have been divided in four groups:(1)Pesticides with linear molecule belonging to the family of aldoxime carbamates.(2)Benzimidazolylcarbamates.(3)Pyrethroids.(4)Pesticides containing one aromatic (heterocyclic in one case) ring within their structure. The experimental work consists of non isothermal thermogravimetric analysis with 5% oxygen in helium, using a TG-DSC-MS system equipped with a Skimmer device that ensures the simultaneousness of thermogravimetric analysis with the analysis of evolved gas and rules out the possibility of secondary reactions in the gas phase. Results have been analyzed in order to highlight similarities and differences in the modes of decomposition of pesticides within and among the four mentioned groups. The influence of oxygen and the yield in gaseous products has also been addressed. © 2007 Elsevier B.V. All rights reserved
Mechanical and chemical characterization of hard anodized cooker grids made in Al-Si alloy
No full text
Cold Spinning of Nimonic 75 Parts: Microstructure Evolution and Heat Treatment
No full textNimonic 75 sheets were cold-spun under different processing conditions and then heat-treated. The microstructure evolutions occurring during the process were studied and discussed in details. The results obtained showed the feasibility of the process when adopting low values of the tool feed rate. Metal spinning produces a deformed microstructure, different in the several areas of interest of the final component. The chosen heat treatment promoted the annealing of the material across the whole part
Chemical Machining of Copper-Based Aerospace Alloys Produced Through Additive Manufacturing: A Preliminary Approach to Improve Surface Quality
No full textAdditive Manufacturing (AM) is transforming the production of high-performance components, particularly in the aerospace sector. However, the surface quality of AM products often does not meet industry standards, necessitating additional treatments. Chemical machining processes are especially advantageous for preserving the intricate geometries of AM parts, yet their application can be challenging for certain metals due to the presence of alloying elements. The objective of this study is to evaluate the enhancement of surface properties, with a focus on roughness reduction, in GRCop-42 components fabricated via powder bed fusion technology, through the application of chemical machining treatments. Two distinct chemical machining solutions were considered: one formulated with ferric chloride and the other composed of a mixture of sulfuric and nitric acids. Furthermore, two experimental setups were implemented to assess the efficacy of ultrasound assistance during the chemical machining process. The results demonstrated that both chemical solutions effectively removed surface material, with the integration of ultrasound significantly accelerating the process. Surface roughness was reduced by up to 13 pct and the steepness of the surfaces was markedly decreased, achieving a nearly uniform finish. However, the utilization of ultrasound with the lower viscosity solution resulted in cavitation erosion, which created undesirable cavities on the surface
- …
