Navegando por Assunto "Metalurgia"

Agora exibindo 1 - 5 de 5

Acesso aberto (Open Access)
Análise do processo de difusão atômica no estado sólido em sistemas unidirecionais e radiais
(Universidade Estadual de Campinas, 1991-03-14) MOREIRA, Antonio Luciano Seabra; SANTOS, Rezende Gomes dos; http://lattes.cnpq.br/8824197696621614
In this work an analytical method is proposed to study diffusion pro¬cess in the solid state in binary systems consisting of only one phase with unidirectional, cylindrical and spherical atomic fluxo Initially a literature survey is carried out regarding some of the most important methods applied to diffusion process in these systems. The method is developed from the differential equation which treats this process in systems with unidirectional atomic flux, that is modified by geometric correlation and convenient changes of variables. The modified differential equation is solved by using a well known exact solution based on the error function and equations are obtained to analyse both the position of the diffusion interface as a function of time and the concentration profiles as a function of the position and time. The predictions furnished by the analytical method are compared with numerical results. A comparative study of diffusion process in planar, cylindrical and spherical geometries is ais o presented. Finally possible applications of the proposed method to the solution of practical problems are discussed.
Acesso aberto (Open Access)
Desenvolvimento de um método para a análise da solidificação de metais superaquecidos em moldes cilíndricos refrigerados
(Universidade Estadual de Campinas, 1983) MOREIRA, Antonio Luciano Seabra; SANTOS, Rezende Gomes dos; http://lattes.cnpq.br/8824197696621614
This work presents a theoretical-experimental study on the solidification of metals, initially at a temperature above the melting point, in cooled cylindrical moulds. A literature survey was carried out regarding the heat transfer methods applied to solidification in metal/mould systems. Using a radial water cooled device simulating the solidification of cylindrical geometries, experimental values of the solidified thickness as function of time were obtained. A method was developed to analyse the solidification kinetics of superheated metals in cooled cylindrical moulds and the predictions furnished by this method were compared with the experimental data. Possible applications of the proposed method to the solution of practical problems in the foundry process 3re presented. Finally a comparative study of the solidification kinetics of solidified metals in plane, cylindrical and spherical geometries is presented.
Acesso aberto (Open Access)
Meio século de mineração industrial na Amazônia e suas implicações para o desenvolvimento regional
(2005-04) MONTEIRO, Maurílio de Abreu
THE ESTABLISHMENT of mineral extraction and mineral transformation industries in the Western Brazilian Amazon in the last five decades created recurrent and widespread expectations of a fast regional industrialization resulting from "comparative advantages" brought by the fulfillment of the world demand for mineral commodities. Mineral and metallurgic activities have proven nevertheless to have a very limited capacity to foster broad and socially rooted development dynamics. This phenomenon may be partially explained by the particular dynamics of technological innovation in those industries, by the institutional environment in which they are embedded and finally by the secondary role played by the social, cultural and ecological characteristics of the region in order to guarantee a competitive valorization of the mineral resources of the Western Amazon.
Acesso aberto (Open Access)
Mineração industrial na Amazônia e suas implicações para o desenvolvimento regional
(2005-06) MONTEIRO, Maurílio de Abreu
The commercial development of mineral resources in the eastern Brazilian Amazon has taken place over the last five decades. In spite of the range of minerals that have been extracted and processed and the different historical periods, the repercussions of the development of certain regional areas have certain important specificities and have a certain logic and characteristics in common. This article synthesizes the macro-level scenarios in which mineral extraction and transformation companies have become established in the region . It also analyzes the limitations of the development of such activities have with respect to promoting and fostering broad and socially rooted development.
Acesso aberto (Open Access)
Regiões do entorno dos projetos de extração e transformação mineral na Amazônia oriental
(2005-12) COELHO, Maria Célia Nunes; MONTEIRO, Maurílio de Abreu; LOPES, Adaise Gouvêa; LIRA, Sérgio Roberto Bacury de
The tentative strategies in the modernization of Brazilian Oriental Amazon happened frequently to the induction in the spatial concentration of great amount of capitals and it resulted the appearance of large mineral-metallurgic plants in the region. The article analyses the main changes occurring in the cities around the mineral extraction and transformation operations contrary to the governmental predictions that there was limited capacity for these activities to promote the quality of life in this region.