Devido a necessidade de redução do consumo dos derivados de petróleo, faz-se necessária a procura da substituição destes por outras fontes viáveis no processo de cementação. Este trabalho apresenta um estudo para viabilização da cementação gasosa através da dissociação do álcool etílico diluído com gás nitrogênio. Foram feitos estudos termodinâmicos, com base em análise química das amostras dos gases retiradas do forno, analisados por um infra vermelho. Com análise dos gases CO, CO2, CH4 pode-se determinar as atividades do carbono nos gases (ag) e o coeficiente de velocidade de transporte de carbono da atmosfera para a superfície metálica (&#946), nas temperaturas de 870ºC, 900ºC, 930ºC, sendo que as atmosferas cementantes nestas temperaturas foram diluídas com diferentes porcentagens de gás nitrogênio. Com os resultados foi possível concluir que as diluições não interferiram no potencial de carbono, mas foi a grande responsável na diminuição no tamanho das camadas cementadas. / Nowadays, due to the need of reduction of the consume of petroleum derivative products, the substitution of these products for others sources is really necessary. This work presents a viability study of carburizing dissociation of ethanol diluted in nitrogen study gas. Thermodynamics studies were carried out with chemical analysis of gas samples from furnace using infrared analyser. CO, CO2 and CH4 gas analysis were used to determine the gas carbon activity (ag) and the carbon coefficient of transport velocity from atmosphere to the metallic surface (&#946), for the temperature of 870°C, 900°C and 930°C. The carbuzing atmosphere for these temperatures were diluted with different percentages of nitrogen gas. With carbon potential, but it was the mean responsible for the size reduction of case carburized.

Devido a necessidade de redução do consumo dos derivados de petróleo, faz-se necessária a procura da substituição destes por outras fontes viáveis no processo de cementação. Este trabalho apresenta um estudo para viabilização da cementação gasosa através da dissociação do álcool etílico diluído com gás nitrogênio. Foram feitos estudos termodinâmicos, com base em análise química das amostras dos gases retiradas do forno, analisados por um infra vermelho. Com análise dos gases CO, CO2, CH4 pode-se determinar as atividades do carbono nos gases (ag) e o coeficiente de velocidade de transporte de carbono da atmosfera para a superfície metálica (&#946), nas temperaturas de 870ºC, 900ºC, 930ºC, sendo que as atmosferas cementantes nestas temperaturas foram diluídas com diferentes porcentagens de gás nitrogênio. Com os resultados foi possível concluir que as diluições não interferiram no potencial de carbono, mas foi a grande responsável na diminuição no tamanho das camadas cementadas. / Nowadays, due to the need of reduction of the consume of petroleum derivative products, the substitution of these products for others sources is really necessary. This work presents a viability study of carburizing dissociation of ethanol diluted in nitrogen study gas. Thermodynamics studies were carried out with chemical analysis of gas samples from furnace using infrared analyser. CO, CO2 and CH4 gas analysis were used to determine the gas carbon activity (ag) and the carbon coefficient of transport velocity from atmosphere to the metallic surface (&#946), for the temperature of 870°C, 900°C and 930°C. The carbuzing atmosphere for these temperatures were diluted with different percentages of nitrogen gas. With carbon potential, but it was the mean responsible for the size reduction of case carburized.

The aim of this work was to systematically study how the microstructure evolution is affected by the carbon activity in WC-Ni cemented carbides. Seven WC-9.59at%Ni alloys with different carbon activity were sintered at 1500 °C. From investigating these alloys, the carbon window has been experimentally evaluated using light optical microscopy and compared to theoretical carbon window calculated using Thermo-Calc. The overall microstructure of cross sections and raw surfaces have been investigated using scanning electron microscopy. Finally, the WC grain size and distribution have been evaluated using electron backscatter diffraction. It was found that the experimental carbon window was slightly wider than the theoretical carbon window. The WC grain size increased and the grain size distribution got wider with increasing carbon activity. In addition, the largest WC grains showed the largest grain growth by increasing carbon activity. By comparing the present results of grain size and distribution of WC-Ni to previous results of WC-Co, it was found that the WC grain growth was more pronounced and more influenced by the carbon activity.