George Carlos dos Santos Anselmo

Comportamento higroscópico do extrato seco de urucum (Bixa Orellana L)

Neste trabalho, objetivou-se determinar a higroscopicidade do urucum na forma de extrato seco. Neste estudo foram obtidas as atividades de agua do extrato seco de urucum para as temperaturas de 10 a 50oC e teores de agua entre 6 e 22% base umida. A metodologia empregada para as determinacoes foi o metodo dinâmico em que se utilizou o equipamento Thermoconstanter Novasina TH-2. Para os resultados experimentais aplicaram-se as equacoes propostas por Henderson modificada por Thompson e Henderson modificada por Cavalcanti Mata e Peleg. Por meio das analises dos parâmetros encontrados concluiu-se que a equacao que melhor se ajusta aos dados experimentais e a equacao de Henderson modificada por Cavalcanti Mata e que as isotermas de adsorcao de agua do extrato de urucum seco se comportaram sigmoidalmente, sendo consideradas do tipo II.

INFLUÊNCIA DA TAXA DE RESFRIAMENTO NAS TEMPERATURAS DE TRANSFORMAÇÃO E NAS MICROESTRUTURAS DE LIGAS TiNiCu COM EFEITO DE MEMÓRIA DE FORMA SOLIDIFICADAS RAPIDAMENTE

* Contribuição técnica ao 70o Congresso Anual da ABM – Internacional e ao 15o ENEMET Encontro Nacional de Estudantes de Engenharia Metalúrgica, de Materiais e de Minas, parte integrante da ABM Week, realizada de 17 a 21 de agosto de 2015, Rio de Janeiro, RJ, Brasil. INFLUÊNCIA DA TAXA DE RESFRIAMENTO NAS TEMPERATURAS DE TRANSFORMAÇÃO E NAS MICROESTRUTURAS DE LIGAS TiNiCu COM EFEITO DE MEMÓRIA DE FORMA SOLIDIFICADAS RAPIDAMENTE*

Study of Heat Treatment on Phase Transformation of Ni-44,8 wt% Ti Ribbons Obtained by Melting Spinning

Shape memory alloys (SMAs) represent a unique class of materials that undergo a reversible phase transformation (martensitic transformation) allowing these materials to display dramatic pseudoelastic stress-induced deformations and shape memory temperature-induced deformations that are recoverable. Among the known shape memory alloys, NiTi is the most commonly used because of its excellent mechanical properties, corrosion resistance and biocompatibility. This work studied the influence of two parameters of heat treatment (temperature and time) on martensite phase transformation temperature (MS) in a Ni-Ti (48,8 wt % Ti) shape memory alloy, using a factorial design (22). The aim of our research was to establish a mathematic model of the technological process, useful for controlling of martensite phase transformation temperature. The two factors, temperature and time, have an important influence on MS.

Influence of the particle size on phase transformation temperatures of Ni-49at.%Ti shape memory alloy powders

It is important to control the martensitic transformation start temperature (Ms) of Ti–Ni alloys because it determines the temperature range over which the shape memory effect and superelasticity appear. Powder metallurgy (PM) is known to provide the possibility of material-saving and automated fabrication of at least semi-finished products as well as net-shape components for NiTi alloys. In this study powder with different particle sizes was subjected by gas atomization. The evolution of the control the martensitic transformation start temperature (Ms) was studied by differential scanning calorimetry. The effect of the particle size of powders on the transformation temperatures behaviors was discussed.