Advanced Plasma Nitriding for Aluminum and Aluminum Alloys
Low hardness and wear resistance of aluminum alloys limit their use in practical application to automotive parts. Formation of hard aluminum nitride (AlN) layer on the surface can prolong the life time of aluminum automotive parts. Plasma nitriding was selected in the present study to form AlN layer on aluminum alloys. This processing is an environmental friendly method because of its low gas and energy consumption. Normal plasma nitriding requires long processing time to successfully form AlN layer. For advancing this surface treatment, refining microstructure and micro-alloying processes are proposed to activate the formation of AlN by plasma nitriding. Bulk Mechanical Alloying is used not only to make grain-size refinement but also to carry out micro alloying with addition of 1 mass%Ti. The formation rate of AlN layer is improved from 4:2 � 10 � 5 mm/s to 20:8 � 10 � 5 mm/s by microstructure refining. In particular, since the co-formed TiN with AlN works as a template in the initial state nitriding, the micro-alloyed aluminum can be nitrided even without pre-sputtering.
Biofuels and Energy Self-Sufficiency: Colombian Experience
The non-renewable nature of fossil fuels combined with the high level of participation within transportation sector in the total consumption of primary energy and atmospheric pollution, have become the primary forces propelling research of alternative sources for vehicles, mainly those sources derived from biomass. This has resulted in an increased environmental consciousness that seeks to replace fossil fuels or to provide blends that reduce their overall consumption. Mainly searching for these sources in agribusiness, and taking into account that tropical countries play lead roles here in Colombia is where the greatest variety of plant species can be found and where the environmental conditions make production of these more advantageous. The global energy problem leads to express the scope, opportunities and threats that the use and partial replacement of conventional fossil fuels by biofuels or agrofuels represent for the development of a country, focusing in Colombia as a case study. The growing importance of new energy sources, (which can be derived from a variety of crops) and raw materials, which demands high biomass amounts, must generate some level of concern about the possible harmful effects of deforestation, jungle loss and replacement of crop fields essential for human diet (food safety). Not to mention the challenges in the climatic, geographical and physical fields, i.e. on whole nations’ economies (Cortes et al., 2009) . Today, these new energy sources are the new financial, political and even environmental strategies. Their importance is such that currently there are more than 30 raw materials being tested worldwide. Despite this big boost they still do not provide a solution to the global energy crisis (Cortes & Alvarez, 1998). The possibility of using biofuels in the development of cars and engines, has been considered from the very beginning, but only as a result of the current energy and environmental situation, do conditions exist for the shaping of a global biofuels industry. The development of alternate energy has allowed the concepts of biofuel and energy crops gain importance every day, with greater strength in agricultural and energy policies of both industrialized and developing countries. The motivating factors have been, among others, the evident depletion of fossil fuels, the periodic oil crisis and the so-called greenhouse effect caused by the accumulation of CO2 in the atmosphere. Despite of this, it is important to recognize that biofuels will not end industrialized countries oil dependency, because there will not be enough land and water to meet the energy requirements of the automotive industry.
THE ATLANTIC SLAVE TRADE AND COLONIALISM: REASONS FOR AFRICA’S UNDERDEVELOPMENT?
It is probably an understatement to assert that Africa, the world’s second largest continent, is underdeveloped compared with other continents. Two major exogenous factors often cited for Africa’s development crisis are the so called ‘dual historical injustices’ – the Atlantic slave trade and colonialism. It is often pointed out that while the former almost completely arrested and retarded Africa’s demographical growth for more than three centuries, evoked a perennial state of acrimony and warfare and created a tense and unprecedented atmosphere of insecurity which hindered economic activities and stifled local entrepreneurship and technological drive and dislocated Africa’s socio-economic and political structures and institutions; the latter tied African countries to the apron strings of western imperial powers thereby rendering the pre-conditions necessary for socio-economic and political transformation unachievable. This paper contends that while the history of Africa’s underdevelopment may be traceable to the Atlantic slave trade and colonialism, African leaders had made enormous contributions to the continent’s underdevelopment and backwardness. The paper concludes that irresponsible and irresponsive leadership, vampirism and prodigality, corruption, lack of respect for democratic ideals, insecurity, endemic civil wars, nepotism, etc are the fundamental causes of Africa’s underdevelopment.