TiB2 nanostructured coating for GFRP injection moulds

In the injection moulding of polypropylene reinforced with hard glass fibres, die materials are commonly subjected to severe abrasive wear. In order to improve its wear resistance, an unbalanced magnetron sputtering PVD compositional monolayered coating has been produced. The film was composed by a nanostructured TiB2 monolayer. Microstructure characterization and thickness evaluation were conducted by scanning electron microscopy (SEM). Film topography and roughness were accessed by SEM and Atomic Force Microscopy (AFM). The phase analyse was investigated by X-ray diffraction (XRD), using Cu Kalpha radiation. Scratch tests were conducted in order to study the film adhesion to the substrate. Load-Displacement curves (nanoindentation analysis) allowed measuring the film hardness and Young's modulus. A ball-cratering tribometer was used to determine the micro-abrasion laboratorial wear resistance, under different tests conditions, using SiC particles in distilled water slurry. At the end of these tests, the worn surfaces were analyzed by SEM and Energy Dispersive X-ray Spectroscopy (EDS) in order to compare these results with some other coatings already tested in the same conditions. To test the practical wear resistance, 135000 injection cycles were done in a plastic injection industrial mould. Coated samples were put on the plastic feed canal, after a turbulent zone. In these tests, a 30% (wt) glass fibres reinforced polypropylene was used. Worn sample surfaces were analyzed by SEM after 45.000 and 90.000 cycles. Image analyses were made in order to evaluate the damage increases and to observe the wear mechanisms involved.

Global material analysis on phosphorus flows, supply horizon and impact assessment on phosphorus depletion

Different problems are daily discuss on environmental aspects such acid rain, eutrophication, global warming and an others problems. Rarely do we find some discussions about phosphorus problematic. Through the years the phosphorus as been a real problem and must be more discussed. On this thesis was done a global material flow analysis of phosphorus, based on data from the year 2004, the production of phosphate rock in that year was 18.9 million tones, almost this amount it was used as fertilizer on the soil and the plants only can uptake, on average, 20% of the input of fertilizer to grow up, the remainder is lost for the phosphorus soil. In the phosphorus soil there is equilibrium between the phosphorus available to uptake from the plants and the phosphorus associate with other compounds, this equilibrium depends of the kind of soil and is related with the soil pH. A reserve inventory was done and we have 15,000 million tones as reserve, the amount that is economical available. The reserve base is estimated in 47,000 million tones. The major reserves can be found in Morocco and Western Sahara, United Sates, China and South Africa. The reserve estimated in 2009 was 15,000 million tone of phosphate rock or 1,963 million tone of P. If every year the mined phosphate rock is around 22 Mt/yr (phosphorus production on 2008 USGS 2009), and each year the consumption of phosphorus increases because of the food demand, the reserves of phosphate rock will be finished in about 90 years, or maybe even less. About the value/impact assessment was done a qualitative analysis, if on the future we don’t have more phosphate rock to produce fertilizers, it is expected a drop on the crops yields, each depends of the kind of the soil and the impact on the humans feed and animal production will not be a relevant problem. We can recovery phosphorus from different waste streams such as ploughing crop residues back into the soil, Food processing plants and food retailers, Human and animal excreta, Meat and bone meal, Manure fibre, Sewage sludge and wastewater. Some of these examples are developed in the paper.

Reabilitação termo-higrométrica de edifícios de estabelecimentos de ensino construídos entre a década de 60 e 90

Em consequência da elevada permanência das pessoas em espaços interiores de edifícios, surge actualmente uma maior preocupação com o conforto térmico e qualidade do ar no seu interior. Apesar da grande evolução tecnológica dos sistemas de conservação de energia térmica e controle da qualidade do ar interior (QAI) na construção, os edifícios existentes acabam por não acompanhar essa evolução, apresentando um comportamento térmico e higrométrico que por vezes podem comprometer quer o conforto, quer a saúde e actividades dos seus utilizadores. Nos estabelecimentos de ensino, o comportamento termo-higrométrico assume um papel importante face à permanência diária de um grande número de crianças e jovens no seu interior. Com este estudo pretende-se caracterizar a qualidade do ambiente no interior de oito escolas, através de uma análise aos principais parâmetros de natureza higrotérmica de oito salas de aulas, tais como: a temperatura (ambiente e superficial), a humidade relativa (do ambiente e da superfície da envolvente exterior opaca), bem como o nível de escoamento do ar interior. Neste trabalho são apresentados os resultados das medições efectuadas em oito salas de aula que permitiram a comparação de características termo-higrométricas entre as respectivas escolas. É ainda apresentada a estimativa do nível de conforto térmico face às condições ambientais registadas, bem como a análise do risco de ocorrência de condensações interiores.