Search results for "Metallurgy"
showing 10 items of 1419 documents
Friction behaviour of heat isolating coatings in machining: mechanical, thermal and energy-based considerations
2003
Abstract This paper deals with possible modifications of the frictional behaviour exhibited during the cutting process resulting from the influence of the most-commonly used heat isolating coatings deposited on a WC-Co carbide substrate. For this study, three- and four-layered coatings with intermediate Al 2 O 3 ceramic layer and a monolayer TiAlN coating, which offer superior thermal protection of the carbide substrate, were examined. Orthogonal cutting tests were carried out by end-turning medium carbon steel and austenitic stainless steel workpieces. The experimental study was aimed at determining the fundamental frictional characteristics: dimensions of the tool-chip contact area, the f…
Comparison of the friction and wear properties of titanium and oxidised titanium in dry sliding against sintered high speed steel HS18-0-1 and agains…
2005
Abstract The paper presents the results of conformal pin-on-disc tribological tests concerning the hard oxidised zone, α-Ti(O), created at the surface of a titanium specimens sliding against the sintered and hardened up to 850 HV30, Grade T1 high speed steel (HS18-0-1) counterspecimens. Comparison with the results obtained for the tests performed against hardened up to 620 HV30 C45 carbon steel counterspecimens has been done. Testing was carried out at room temperature and at unlubricated conditions. After tests the structures and compositions of the worn surfaces and wear debris were a subject of LOM, SEM observations and X-ray microanalyses. In comparison with the baseline—the Ti/T1 HSS c…
Prediction of Tool Wear Progress in Machining of Carbon Steel using different Tool Wear Mechanismsl
2008
In this paper the prediction of tool wear on carbide uncoated tools was taken into account. In particular, two different tool wear models based on the diffusion mechanism and on the abrasion mechanism were considered. The calibration of the utilized models was done using the results obtained by experimental analysis performed on an orthogonally machined AISI 1020 tube. Once the calibration was executed, numerical simulations, for both the utilized tool wear models, were simultaneously performed with the aim to test the capability of the proposed numerical procedure. The comparison between the two tool wear mechanisms for predicting the flank tool wear is discussed in the paper.
The role of coatings in controlling the cutting process when turning with coated indexable inserts
1998
Abstract This paper is concerned with the variations in the specific cutting pressure and the tool–chip interface temperature that occur when machining a medium carbon steel and an austenitic stainless steel with TiC-, TiC/TiN- and TiC/Al2O3/TiN- coated inserts. Extensive experimental studies involving the cutting force and the interface temperature were performed. A standard thermocouple embedded in the workpiece was used to determine the cutting temperature. Two new parameters were introduced in order to compare both the mechanical and thermal loadings of the tool–chip contact for coated flat-faced and grooved inserts. Some optimal coating structures for high speed machining of these stee…
Friction and wear properties of titanium and oxidised titanium in dry sliding against hardened C45 steel
2004
Abstract The aim of the paper is to present the results of conformal pin-on-disc tribological tests concerning the hard oxidised zone created in superficial layer of a titanium specimen sliding against the hardened to a hardness of 690 HV carbon C45 steel counterspecimen. Tribological testing was carried out at room temperature and at unlubricated conditions. After tests the structures and chemical compositions of the wear debris and worn surfaces were a subject of SEM and X-ray investigations. In comparison with the baseline the technical quality titanium/C45 steel couple, the wear and lifetime performance of the oxidised titanium/steel C45couple was markedly superior. Dominant wear debris…
Study of Coating/Work Material Interaction in Turning with Chip Forming Inserts
1997
This paper presents some interesting and novel results of an experimental study on the influence of the coating structure on the behaviour of the tribo-contact between the tool and the chip. The experiments involved TiC, TiC/TiN and TiC/Al2O3/TiN — coated flat-faced and grooved inserts in conjunction with a medium carbon steel and an austenitic stainless steel. Extensive experimental studies involving the cutting force and the tool-chip interface temperature were carried out. Two new parameters were introduced in order to compare both the mechanical and thermal loadings of the tool-chip contact for the two shapes of the rake face. Some optimal coating structures for high speed machining of …
Thermal Characterization of the Chip-Tool Interface When Using Coated Turning Inserts
2000
Abstract This paper reports some results of extensive experimental investigations of the thermal interactions between the coating/substrate and the moving surface of the chip. Semi-orthogonal cutting when bar turning a medium carbon steel and an austenitic stainless steel was carried out. Both flat-faced and grooved inserts coated with TiC, TiC/TiN, and TiC/Al 2 O 3 /TiN were tested. A standard K-type thermocouple embedded in the workpiece was used to convert measured efm's to the interfacial temperatures. In addition, the chiprake contact length and the area of contact were determined by using computer processing of scanned contact images. The minimum steady-state temperature at the interf…
Pd supported on magnetic carbon coated halloysite as hydrogenation catalyst: Study of the contribution of carbon layer and magnetization to the catal…
2019
Abstract In this article, a magnetic carbon-coated halloysite nanoclay (Hal) was prepared through introduction of hydrothermally carbonized glucose (Glu) on Hal followed by the immobilization of magnetic nanoparticles (MNPs) and incorporation of resorcinol-formaldehyde polymeric shell (RF) and carbonization. The resulting composite was then successfully applied for the immobilization of Pd nanoparticles to afford Pd@Hal@Glu-Fe-C that could efficiently promote hydrogenation of nitroarenes in the aqueous media at low temperature. The catalyst exhibited high selectivity toward nitro group. Moreover, it was highly recyclable with low MNPs and Pd leaching. To elucidate the contribution of each c…
The Preparation and the Characterisation of some Ternary Titanium Oxide Pkotocatalysts.
1987
TiO 2 catalysts, of moderate surface areas and minimal porosities, containing various nominal quantities of iron have been prepared. E.s.r spectra indicate that Fe 3+ is well dispersed in coprecipitated samples, and in impregnated Tioxide samples, when the iron concentration is
Hydrothermal Synthesis of Cobalt Ferrite Nanosized Powders
2015
Cobalt ferrite powders are synthesized by the co-precipitation technology, combined with the hydrothermal synthesis method and crystallite size, specific surface area (SSA), magnetic properties of synthesized products are obtained. All the synthesized ferrites are nanocrystalline single phase materials with crystallite size of 10-16 nm the SSA of 60±5 m2/g and the calculated particle size of 20±2 nm. Synthesized Co ferrites are characterized by the saturation magnetization MS of 59-60 emu/g, remanent magnetization Mr of 23 emu/g and coercivity Hc of 570-650 Oe.