19 documents found, page 1 of 2
Effect of different acidic media on the corrosion behaviour of hardmetals with ...
Pereira, P.; Rocha, A. M. Ferro; Sacramento, J.; Oliveira, F. J.; Malheiros, L. F.; Senos, A. M. R.; Bastos, AlexandreHighly corrosive agents, such as saltwater, hydrogen sulphide, hydrofluoric or hydrochloric acids, are frequently found in oil and gas exploration. The high costs associated with the premature replacement of equipment damaged by corrosion and the consequent production losses justify the search for more resistant materials. In this work, the corrosion behaviour of cemented carbides with different Ni-based binder...
Corrosion resistance of WC hardmetals with different Co and Ni-based binders
Pereira, P.; Rocha, A.M. Ferro; Sacramento, J.; Oliveira, F. J.; Senos, A. M. R.; Malheiros, L. F.; Bastos, AlexandreIn this work, industrially relevant WC composites with alternative binders (Ni, CoNi, NiCr, CoCr, CoNiCr and NiCrMo) were produced and their corrosion resistance in 0.5 M NaCl was compared to conventional WC-Co system. The main objective is to develop hardmetals with higher corrosion resistance to extend the lifetime of tools and equipment, reducing the demand for new parts and maintenance, thus decreasing the ...
Abrasive wear resistance of WC-Co and WC-AISI 304 composites by ball-cratering ...
Vilhena, L. M.; Fernandes, C. M.; Soares, E.; Sacramento, J.; Senos, A. M. R.; Ramalho, A.In the present work, the effect of different binder materials on the tribological properties of cemented carbides was studied. Flat samples of conventional WC-Co, and newly developed WC-AISI 304 stainless steel (SS) composites with and without carbon addition were surface finished by grinding and polishing. Comparative experiments were performed using a ball-cratering tribometer. Worn surfaces were characterize...
Copper wettability on tungsten carbide surfaces
Silva, V. L.; Fernandes, C. M.; Senos, A. M. R.The wetting behavior of copper on tungsten carbide surfaces was investigated through the sessile drop method, at 1080 degrees C, in vacuum atmosphere. Tests were performed on three different types of substrates: (i) commercial sample of WC-Co with 3.5 wt% of cobalt; (ii) WC thin film sputter-deposited on the aforementioned commercial WC-Co sample and (iii) WC sample processed by hot pressing. The lowest final c...
Target nanomaterials at CERN-ISOLDE: synthesis and release data
Ramos, J. P.; Gottberg, A.; Augusto, R. S.; Mendonca, T. M.; Riisager, K.; Seiffert, C.; Bowen, P.; Senos, A. M. R.; Stora, T.Five different nanostructured target materials were tested and operated at ISOLDE in the year of 2014, three of them being carbon-based nanocomposites. In most cases such target materials have higher radioisotope intensities than standard targets and with apparently longer release characteristics. Here, an isotope release profile from a standard calcium oxide (CaO) powder target is compared to the nanostructure...
Corrosion behaviour of WC-10% AISI 304 cemented carbides
Oliveira, A. B.; Bastos, A. C.; Fernandes, C. M.; Pinho, C. M. S.; Senos, A. M. R.; Soares, E.; Sacramento, J.; Zheludkevich, M. L.; Ferreira, M. G. S.The corrosion behavior of tungsten carbide hard metal composites with AISI 304L stainless steel as binder matrix and a WC–Co composite with similar grain size and binder content was investigated using electrochemical techniques (open circuit potential monitoring, current-potential curves, electrochemical impedance spectroscopy, scanning vibrating electrode technique) and scanning electron microscopy.
Structural and electrical characteristics of rhombohedral lead zirconate titana...
Pérez, J. A.; Soares, M. R.; Almeida Paz, Filipe A.; Klinowski, J.; Senos, A. M. R.; Mantas, P. Q.Two PbZrxTi1-xO3 (PZT) single crystals, from a batch prepared by the flux method, were analysed to assess their chemical composition. The two single crystals were found by electron microprobe analysis to have the chemical compositions PbZr0.60Ti0.40O3 and PbZr0.65 Ti0.35O3. X-ray diffraction at -93 degrees C revealed that both crystals have the R3m space group, which means that the R3m <-> R3c phase transition ...
Sintering kinetics of nanometric calcium oxide in vacuum atmosphere
Ramos, J. P.; Fernandes, C. M.; Stora, T.; Senos, A. M. R.A recent application for nanometric CaO powder is its use as a spallation target material for the production of isotope beams at CERN. The stability of the nanostructure at high operation temperatures is a crucial feature to provide stable and improved isotope release rates. Prior to operation, sintering studies under thermal conditions similar to those of the target operation are required to establish the micr...
Increased surface area during sintering of calcium phosphate glass and sodium c...
Davim, E. J. C.; Fernandes, M. H. V.; Senos, A. M. R.Glass scaffolds were obtained by the salt sintering method, using mixtures of calcium phosphate glass, 25.42%SiO2-10.89% P2O5-32.68%CaO-31%Mg0(mol%), and salt, NaCl, pressed and sintered bellow the salt melting point, followed by leaching of the salt in water. The sintering behaviour of glass/salt powder mixtures was followed by dilatometry, BET and SEM. It was found that the specific surface area (SSA) of supp...
Corrosion behaviour of WC-10% AISI 304 cemented carbides
Oliveira, A. B.; Bastos, A. C.; Fernandes, C. M.; Pinho, C. M. S.; Senos, A. M. R.; Soares, E.; Sacramento, J.; Zheludkevich, M. L.; Ferreira, M. G. S.The corrosion behavior of tungsten carbide hard metal composites with AISI 304L stainless steel as binder matrix and a WC-Co composite with similar grain size and binder content was investigated using electrochemical techniques (open circuit potential monitoring, current-potential curves, electrochemical impedance spectroscopy, scanning vibrating electrode technique) and scanning electron microscopy. (C) 2015 E...