Effects of high temperature plasma immersion ion implantation on wear resistance of Ti-Si-B sintered alloys

AbstractAlthough titanium and its alloys own good mechanical properties and excellent corrosion resistance, these materials present poor tribological properties for specific applications that require wear resistance. In order to produce wear-resistant surfaces, this work is aimed at achieving improvement of wear characteristics in Ti–Si–B alloys by means of high temperature nitrogen plasma immersion ion implantation (PIII). These alloys were produced by powder metallurgy using high energy ball milling and hot pressing. Scanning electron microscopy (SEM) and X-ray diffraction identified the presence of α-titanium, Ti6Si2B, Ti5Si3, TiB and Ti3Si phases. Wear tests were carried out with a ball-on-disk tribometer to evaluate the friction coefficient and wear rate in treated and untreated samples. The worn profiles were measured by visible light microscopy and examined by SEM in order to determine the wear rates and wear mechanisms. Ti–7.5Si–22.5B alloy presented the highest wear resistance amongst the untreated alloys produced in this work. High temperature PIII was effective to reduce the wear rate and friction coefficient of all the Ti–Si–B sintered alloys

Gestão de organizações do terceiro setor em São José dos Campos

Orientação: Prof. Dr. Marcio S. LuzDissertação (Mestrado) - Universidade de Taubaté, Programa de Pós-graduação em Administração, Mestrado em Gestão e Desenvolvimento Regional,Taubaté, 2006.Made available in DSpace on 2019-08-23T18:30:35Z (GMT). No. of bitstreams: 1 Jose Fernando Barriento Lopes.pdf: 888160 bytes, checksum: 0e7aeda68a19ba571b9b4c2e554fc5f3 (MD5) Previous issue date: 2006Resumo: A fim de perceber se as práticas administrativas estão alinhadas com os conceitos de profissionalização associados ao Terceiro Setor, este trabalho investiga a gestão institucional e organizacional de diversas instituições na cidade de São José dos Campos. A gestão institucional refere-se aos fatores estratégicos e de liderança, enquanto que a organizacional envolve os modelos e características de gestão adotadas. É sabido que a sustentabilidade das organizações dessa natureza se torna cada vez mais dependente do desempenho percebido por seus patrocinadores e pela opinião pública. O financiamento de iniciativas sociais preconizadas pelas organizações desse setor está ficando mais seletivo, o que pode levá-las a adotar linhas de ação e decisão que se assemelham às organizações privadas. A adoção de práticas instrumentais na busca por eficiência, característica do Primeiro e Segundo Setores, deve conduzir a melhoria de resultados, porém, pode causar um distanciamento irreversível de identidade no setor. Por isso, para captar as nuances envolvidas, escolheu-se realizar uma pesquisa de campo com finalidade exploratória e explicativa. Os dados foram captados por um formulário desenvolvido pelo autor e baseado em bibliografia atual deautoridades reconhecidas nos assuntos abordados. A análise da pesquisa permite concluir que a realidade de profissionalização e o estágio de desenvolvimento da gestão do Terceiro Setor Joseense são bem diferentes das expectativas otimistas acadêmicas.Abstract: In order to perceive weather the administrative practices are aligned with the concepts of professionalism associated to Third Sector, this work aims to investigate the institutional and organizational management of many institutions in the city of São José dos Campos. Institutional management refers to strategic and leadership factors, whereas the organizational management is concerned with the management modelsand characteristics adopted. It is well known that sustainability of such organizations depends upon the performance sponsors and public opinion realize. The financing of social initiatives recommended by those Third Sector organizations has become scarce and has forced these organizations to adopt an action and decision-making process often similar to those of the Second Sector. The adoption of instrumental practices in searchfor efficiency, main characteristic from the First and Second Sectors, should lead to better results, but may cause an irreversible identity distancing to the Third Sector. A field research was chosen for the study for exploratory and explaining purposes. Data were captured by a form developed by the author, based on the contemporary literature from recognized authorities in the approached matters. The analysis process lead to the conclusion that the reality of the professionalism and development stage for the Third Sector management in São José dos Campos are quite different from the optimistic academic expectations

Study of ceramic block manufacture with the addition of waste from iron ore extraction

This work is intended to study the possibility of adding an amount of waste from iron mining in the ceramic mass. Clay and coal, from Vale do Paraiba, Sao Paulo, Brazil, were used in this research. These raw materials are used in the ceramic block manufacture. Clay and waste were analyzed by X-ray fluorescence and X-ray diffraction, particle size, differential thermal and thermogravimetric analysis. Liquid limit and plasticity index tests were performed in order to determine the amount of waste that which should be used in the ceramic mass. After determining the amount of waste, all samples were uniaxially pressed and sintered at 900 degrees C. Surface roughness measurements, apparent porosity and bulk density technique and three-point flexural tests were also performed to characterize the samples. The results showed that by adding the exact amount of waste, which was determined by the essays, it is possible to manufacture solid bricks

Superficial modifications in TiO2 and Al2O3 ceramics

The properties of hydrophilicity or hydrophobicity of materials are defined mainly, though not exclusively, by their composition, morphology and surface energy. In this work, titanium dioxide (TiO2) and aluminum oxide-alumina (Al2O3) ceramics prepared by uniaxial pressing were studied in terms of surface energy. The surfaces of these ceramics were treated with nitrogen plasma, using a stainless steel reactor excited by a 13,6 MHz radio frequency operating at 50 W input power and 13 Pa nitrogen pressure. The surface morphology was investigated by scanning electron microscopy (SEM) analysis. Surface energy and contact angle measurements were taken using a RAMÉ-HART goniometer. These measurements were taken as function of time, over a 21-day period. The contact angle and surface energy values were found to change by almost 34% in comparison to their initial values immediately following plasma treatment. Nonetheless, the hydrophilic character of the Al2O3 and TiO2 remained constant throughout the test period

Superficial modifications in TiO2 and Al2O3 ceramics

The properties of hydrophilicity or hydrophobicity of materials are defined mainly, though not exclusively, by their composition, morphology and surface energy. In this work, titanium dioxide (TiO2) and aluminum oxide-alumina (Al2O3) ceramics prepared by uniaxial pressing were studied in terms of surface energy. The surfaces of these ceramics were treated with nitrogen plasma, using a stainless steel reactor excited by a 13,6 MHz radio frequency operating at 50 W input power and 13 Pa nitrogen pressure. The surface morphology was investigated by scanning electron microscopy (SEM) analysis. Surface energy and contact angle measurements were taken using a RAMÉ-HART goniometer. These measurements were taken as function of time, over a 21-day period. The contact angle and surface energy values were found to change by almost 34% in comparison to their initial values immediately following plasma treatment. Nonetheless, the hydrophilic character of the Al2O3 and TiO2 remained constant throughout the test period

Properties of glass-ceramics obtained from crystallization of the SiO2-Al2O3-MgO-Li2O system with addition of ZrO2

This paper presents the study results with glass-ceramics obtained from base glass (MgO-Al2O3- SiO2-Li2O system) with addition of ZrO2 as nucleating agent. The glass was melted at 1650 degrees C for 3 h and at a heating rate of 10 degrees C/min. The molten glass was poured into a graphite mold to obtain monolithic samples and also in water in order to obtain particulate material. Such material was grinded and then pressed by both uniaxial and isostatic pressing methods before being sintered. Both the monolithic and pressed samples were performed under two different conditions of heat treatment so that their nucleation and crystallization occurred. In the first one, the samples were heated to 1100 degrees C with a heating rate of 10 degrees C/min. In the second one, there was an initial heating rate of 10 degrees C/min up to 780 degrees C, which was kept for 5 minutes. After that, the samples were heated to 1100 degrees C at a heating rate of 1 degrees C/min. Microhardness analyses showed that base glass presented values around 7.0 GPa. The glass-ceramics obtained from the powder sintering showed microhardness values lower than those obtained from monolithic samples. The highest hardness values were observed in the samples which were treated with two heating rates, whose values were around 9.2 +/- 0.5 GPa. Moreover, the glass-ceramics which were produced with an only heating rate, presented values around 7.1 +/- 0.2 GPa, very close to those observed in the base glass