000001603 001__ 1603
000001603 035__ $$a35162 
000001603 037__ $$aROMDOC-THESIS-2017-1084
000001603 041__ $$arum
000001603 100__ $$aIvan, Nicoleta
000001603 245__ $$aCercetări privind fenomenul degenerării grafitului în stratul superficial al pieselor turnate din fonte cu forme compacte de grafit 
000001603 260__ $$c2011-09-21
000001603 520__ $$aResearch on the graphite degeneration phenomenon in the superficial layer of the iron castings with compact graphite forms Abstract: Experience in a industrial scale production of iron castings containing compacted graphite forms, shows that one of the main defects seen on these is the appearance of graphite degeneration in the superficial layer. The main causes of graphite degeneration (superficial degeneration) are considered to be chemical interactions between liquid iron and molds, which reduces the content of modifying elements, below the required level of toughness. It was found that when the mechanical properties measurements are performed on unprocessed samples and not on processed samples, their mechanical properties are significantly reduced because of the low resistance of superficial layer, which is why it is important to study its impact on the quality of iron castings. Present work, has proposed a broader approach of graphite degeneration phenomenon in the superficial layer of iron castings with compacted graphite forms and possibilities of its reduction, for this purpose, being made a systematic study on current state of research in this field, aiming at a clearer definition of this phenomenon as well as characterization of graphite degeneration way of manifestation, its influence on mechanical properties, and factors influencing the graphite degeneration. Among the experimental program objectives achieved in this thesis include: establishing some correlations between the solidification conditions (molds type, wall thickness, residual Mg level and type of disturbances) and degenerated graphite layer on a hand and cooling curves parameters and cast iron microstructure (graphite and matrix) on the other hand, as well as, possibility of limiting or eliminating the occurrence of degenerated graphite layer. To achieve the objective, were made a series of experiments in 4 experimental programs, in which were studied: molds type and wall thickness influence on graphite degeneration, modification potential and some disturbing factors influence on graphite degeneration, as well as, possibilities to reduce the effect of graphite degeneration in the superficial layer by using some protective coatings.  The experimental results showed that graphite degeneration in the superficial layer of iron castings depends both by mold type and wall thickness, as well as, its modification potential and type of paint, and the main factor determining graphite degeneration was found to be sulfur from mold materials based on furan resin and from paint based on FeS2. There were also obtained significantly lower values of degenerated graphite layer thickness or even eliminate it by using protective coatings based on Mg.
000001603 6531_ $$aTurnare -- Tehnologie mecanică -- Teză de doctorat 
000001603 6531_ $$aFontă -- Turnare -- Teză de doctorat
000001603 6531_ $$aProcesarea materialelor -- Teză de doctorat
000001603 8560_ $$ff_costache@library.pub.ro
000001603 8564_ $$uhttp://romdoc.upb.ro/record/1603/files/$$zAccess to Fulltext
000001603 980__ $$aTHESIS