Effect of cooling rate on properties of plasma nitrided AISI 1010 steel

In this work, AISI 1010 steel samples were plasma nitrided into 20% N 2 100 Pa and 400 Pa for N 2 and H 2 , respectively), temperatures of 500 and 580 °C, during 2 h. Three different procedures for cooling were accomplished after nitriding. In the first procedure the cooling occurred naturally, that is, the sample was kept on substrate holder. In the second one the sample was pulled off and cooling in a cold surface. Finally, in the third cooling process the sample was pulled off the substrate holder down into special reservoir filled with oil held at ambient temperature. The properties of the AISI 1010 steel samples were characterized by optical and electron microscopy, X-ray diffraction, Mössbauer spectroscopy and microhardness tests. Thermal gradient inside the sample kept on substrate holder during cooling process was measured by three inserted thermocouples at different depths. When samples were cooled rapidly the transformation of ϵ-Fe 2 − 3 N to γ′-Fe 4 N was inhibited. Such effect is indicated by the high concentration of ϵ-Fe compound zone. To get solid state solution of nitrogen in the diffusion zone, instead of precipitates of nitride phases, the cooling rate should be higher than a critical value of about 0.95 °C/s. When this value is reached at any depth of the diffusion zone, two distinct diffusion zones will appear. Temperature gradients were measured inside the samples as a consequence of the plasma treatment. It's suggested the need for standardization of the term “treatment temperature” for plasma treatment because different nitrided layer properties could be reported for the same “treatment temperature”.

Aparências da forma e forma do espaço: análise da configuração espacial de residências unifamiliares dos anos 1970 em João Pessoa PB

Assuming that the form of a building shell and its content the spatial form are distinct dimensions of architecture - however indivisible and interdependent -, this study focus, in the light of the Social Logic of Space (HILLIER; HANSON, 1984), on the intrinsic properties through which domestic space was structured in a sample of single-family dwellings built in João Pessoa (PB) during the 1970s - when the vocabulary of modern architecture still prevailed in Brazil though sharing the urban scene with other architectural trends -, in order to investigate regularities or divergences underlying their conception. These dwellings were originally classified (ARAÚJO, 2010a) in five categories defined according to the form of their building shells and to their prevailing construction techniques: (1) Brazilian modern legacy (considered as truly Brazilian modern style); (2) Paulista architecture (that refers to the modern production of São Paulo, Brazil, from the 1950s through the 1970s); (3) experiences of rationalization and prefabrication ; (4) experiences of adaptation to the climate (referring to a design strongly influenced by the hot and humid climate of North-eastern Brazil); and (5) hybrid (to account for a kind of stylistic hybridism that includes formal attributes, which evoke our colonial past). This study aims to determine, through the analyses of nineteen cases that represent each category, whether this taxonomy corresponds to distinct modes of spatial configuration. This research therefore proposes an approach to the classification of domestic architecture based on topological properties. The dwellings spatial organization was represented, quantified and analyzed, their spatial properties explored in consonance with one another and with the literature. Results pointed out that there is no evidence of a reciprocal relationship between the formal look of the built shells and their respective spatial structures

Casas modernas na orla marítima de João Pessoa 1960 a 1974

This paper studies modern houses built in the neighborhoods of Cabo Branco, Tambaú and Manaíra by the seafront in Joao Pessoa, built between 1960 and 1974. We start from the already widespread notion that Brazilian Modern Architecture was inspired by foreign ways, mainly European but also American here recast, adapted, often innovating repertoire and ideas received (Y. BRUAND, 2005; H. SEGAWA, 2002; C. E. COMAS, 2002; C. E. COMAS, 2002; M. M. ACAYABA e S. FICHER, 1982; M. B. C. ARANHA, 2008; F. C. L. LARA, 2001; R. V. ZEIN, 2005; L. E. AMORIM, 1999, C. V. STINCO, 2010). With this look, after a field study, we collected 61 specimens in the collection of the Central Archive of João Pessoa City Hall, in order to identify which reformulations, adaptations or innovations would exist in modern houses built along the coast in João Pessoa. As we try to analyze the houses by what the bibliography had suggested (G. C. ARGAN, 1992; L. CORBUSIER, 2002; C.E.D. e M. ADRIÀ, 2007; K. FRAMPTON, 1997; H. H. HITCHCOCK, 1976; L. BENEVOLO, 2004; R. DE FUSCO, 1992, N . PEVSNER, 2002; M. RAGON, 1986; B. RISEBERO, 1982; E. ROBBINS, 1997; W. J. R. CURTIS, 1982; V. SCULLY, 2003; B. ZEVI, 1984; D. DUNST, 1999; A. COLQUHOUN, 2002; R. WESTON, 2005; A. IÑAKI, 2006; J. PETER, 1994) the starting idea seemed to us not sufficiently developed. So we decided, first, to undertake a literature review comparing speech and image of modern houses most often cited by international and national literature, following a script freely inspired the Vitruvian triad: the functional and spatial (sectorization, guidance, spatiality, movement); constructive aspects (structural elements, modulation, deck, sealing), and aesthetic aspects (composition, apertures, ornaments) (Cap.1), then cast a look under this same route in 61 specimens obtained initially, trying to verify any specificities they would have (Cap.2). Failing to deepen the analysis of all these examples, we chose 10 projects which were redesigned and described in more detail to which we supplement with the aspects of place - location / lot location, access, axiality. (E. C. MAHFUZ, 2002; J. C. MIGUEL, 2000; E. C. CHEREGATI, 2007; M. COTRIM, 2007). (Cap. 3). The documentation and description resulting allowed us to approach some related questions about the canonical transcripts hybridizing, adoptions and any vernacular innovations of modern houses along the coast, We conclude that the appellants and anachronistic elements isolates found in each of the studied bind to the Brazilian Modern Architecture