Estudo da propriedade de resistência de uniäo metalocerâmica entre uma liga semi-nobre de paládio-prata e três sistemas cerâmicos importados, em funçäo de diferentes tempos de oxidaçäo prévia / Study of metalloceramics bond strength property between a seminoble palladium-silver alloy and three ceramic systems, by different periods of previous oxidation

O objetivo deste trabalho foi avaliar a propriedade de resistência de uniäo metalocerâmica em uma liga semi-nobre de Paládio/Prata, marca comercial Pors-On IV (Degussa), frente a diferentes tempos de oxidaçäo prévia (0, 5, 10 e 15 minutos) à aplicaçäo de três sistemas cerâmicos (Duceram, Williams, Noritake). O teste utilizado foi o proposto por CHIODI NETTO (21), que é um teste de cisalhamento modificado a partir do teste proposto por SHELL; NIELSEN (78). Frente aos resultados obtidos chegou-se as seguintes conclusöes: 1) Tanto os grupos controles como os grupos experimentais näo exibiram diferenças estatisticamente significantes entre si; 2) As maiores médias de resistência ao cisalhamento foram obtidas nos grupos: I (Duceram - sem oxidaçäo prévia); II (Duceram - oxidaçäo prévia de 5 minutos e VI) Williams - oxidaçäo prévia de 5 minutos); 3) As menores médias foram encontradas nos grupos que utilizaram o sistema Noritake, independente do uso ou näo de tratamento térmico de oxidaçäo prévia

Spectrophotometric determination of Cu2+ and Pd2+ ions using some acetyl formazans

The formazan compounds have received great attention due to their biological activity and dyeing properties for a variety of fabrics [1,2] Due to their skeleton as good carriers of pi-bonding and chelating properties, they have been used as analytical reagents [3]Malevannyi and Shikhova [4] reported a Spectrophotometric method for the determination of Mn[2+] using 1,5-bis [2-hydroxy-5-sulfophenyl]-3-acetylformazan. Bigma et al. [5] developed a Spectrophotometric procedure for the microdetennination of Cu in Mg metal and some of its Mg alloys using 1,5-di [2-hydroxy-4-nitrophenyl]- 3- acetyl-formazan. Christian [6] reported a method for the determination of lithium using TMC-Crown formazan. Novel pyridyl formazan derivatives were synthesized and the characteristic analytical properties of their complex compounds with various transition metal ions were investigated [7]. The present investigation deals with the use of l,5-diphenyl-3- acetylformazan [I] and l,5-bis[o-carboxyphenyl] -3- acetylformazan [II] for the Spectrophotometric determination of Cu and Pd

Kinetics of Pd [II] extraction with thenoyltrifluoroacetone in carbon tetrachloride

The conditions of the kinetics of extraction of Pd[II] with thenoyltrifluoroacetone [HTTA] in carbon tetrachloride are studied. The extraction rate depends on the pH of the aqueous phase, the concentrations of Pd[II] and reagent and temperature. The activation parameters are also studied through experimental data. In the case of Pd[II] extraction with HTTA the thermodynamic parameters are found to depend on the pH of the aqueous phase