Uspihi materialoznavstva最新文献

{"title":"Modeling of manufacturing processes of thin-walled bushings from porous blanks using direct extrusion and radial compaction","authors":"A. Mikhailov, Ye. Shtefan, O. Mikhailov","doi":"10.15407/materials2023.07.002","DOIUrl":"https://doi.org/10.15407/materials2023.07.002","url":null,"abstract":"The deformation process of powder materials thin-walled bushings manufacture was investigated by computer modeling. Two shape formation bushings schemeswere considered (direct extrusion and radial compaction).A continuum approach was used to create a modeling method. The method is based on rheological models of porous body plastic deformation and the finite element method. The accepted material rheological model allows describing the deformation of both powder and porous blanks. It takes into account the different resistance of these materials in tension and compression. Modeling of the deformation process was carried out in stages, using the method of successive loads. The elastic stresses were determined, the plastic potential was calculated and, if it was necessary, the stresses and material parameters of the model were corrected at each load step. The porosity value is reach maximum in blank and area, that is free from the loads, and the accumulated deformation is reachminimum in direct extrusion. The effect of back pressure leads to a more uniform distribution of these parameters, a decrease in porosity and an increase in the accumulated deformation of the solid phase. During radial compaction of thin-walled bushings, deformation of the material occurs locally. Porosity in the product section increases with increasing radius. Increasing the number of technological transitions with a gradual increase in the forming tool diameter reduces the uneven distribution of residual porosity and its value. However, the unevenness of the porosity distribution over the radius remains. In the process of radial compaction, a burr is formed on the ends of the product. The burr can be reduced by changing the initial shape of the blank. The process of direct extrusion allows obtaining more uniform distribution of residual porosity and accumulated plastic deformation of product material. However, this technological process requires the higher loads application, which leads to less stability of the tool. The radial compaction method (which characterized by local deformation) requires not high loads and allows not powerful equipment using. However, the distribution of residual porosity over the radius of the bushing is uneven. Keywords: plasticity theory, powder materials, computer modeling, finite element method, stress-strain state, porosity distribution.","PeriodicalId":509971,"journal":{"name":"Uspihi materialoznavstva","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139195116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wetting and contact interaction of semconductor oxide materials Ga2O3, In2O3, ZnO with metallic melts in vacuum","authors":"M. Grigorenko, E. Chernigovtsev, O. Durov, V. Poluyanska, A. Ievtushenko","doi":"10.15407/materials2023.07.010","DOIUrl":"https://doi.org/10.15407/materials2023.07.010","url":null,"abstract":"Semiconductor oxide materials such as gallium, indium and zinc oxides play an important role in a development and production of a variety of electronic devices. Experimental studies of these materials allow to define, for example energetic or other physical parameters of the devices created and also to improve existing technologies of their production, metallization and joining of electrocontacts by way of brazing which require additional wetting studies. It should be noted that data on wetting of mentioned oxides by metals are practically absent in literature. Thus a detailed experimental study of the interfacial interaction, adhesion and wetting of Ga2O3, In2O3 and ZnO oxide materials with some pure metal melts (Ga, In, Sn, Au,Ge, Ag, Cu) in vacuum was performed by the sessile drop method using photo- and video- fixing including temporal and temperature dependencies of contact angles. It was found that pure metals don't wet powdery pressed specimens of Ga and In oxides in the temperature range studied and vary in a rather narrow range. For ZnO system the significant effect of experiment temperature and hold-up time on the values of contact angles for some metals (Ga, Ge, Sn, Cu) is observed. For example wetting angles for Ga change from above 90 degrees at low temperatures up to 49 and full spreading at 1173⎯1373 K. This effect may be attributed to the activation of chemical reactions, change of oxide stabilities at high temperatures at the interface. Last metals can be used as adhesive-active additions to base brazing alloy. Keywords: gallium, indium, zinc oxides, semiconductor, wetting, contact interaction, metal melt.","PeriodicalId":509971,"journal":{"name":"Uspihi materialoznavstva","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139190074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}