This paper investigates the three-body wear resistance rates of five restorative dental composite materials at different mastication cycles and compares the results with that of an amalgam material. Five specimens of each material were exposed three-body wear tests using a computer-controlled chewing simulator with steatite balls as the antagonist (1.6 Hz, 49 N load; 120,000, 240,000 and 480,000 mechanical cycles; and thermal cycling between 5 and 55°C at 5 min/cycle and 3000 cycles) immersed in a poppy seed slurry (three-body wear environment). Initially, the microhardness values of the composite materials in the Vicker’s hardness (HV) scale were determined. The mean volume loss of the worn surfaces was measured with a three-dimensional profilometer. Means and standard deviations were calculated, and statistical analysis was performed using one-way ANOVA (α=0.05). Additionally, scanning electron microscopy analysis was performed to examine the wear tracks on the surface. The interactions between the composite resin and mean volume loss were found to be significant. The three-body wear rates for the composites Durafil and Kalore composite were significantly higher than those of the other composites and the amalgam irrespective of the number of mastication cycles. Filtek Z250 and Filtek Supreme composite resins had good three-body wear resistance similar to that of the amalgam. However, this study suggests that the correlation between Vicker’s hardness and three-body wear resistance is not significant.
ÖzRapid depletion of fossil fuel resources as well as concerns for foreign dependence in meeting energy needs have led researches for alternative fuels. Biodiesel, which can be obtained from many renewable resources such as vegetable oil and animal fat through transesterification, is the most attractive alternative fuel for cars, especially for being environmentally friendly. However, there are some cons, too. The presence of water and free fatty acids in the biodiesel makes it more corrosive than petrol-diesel, and this is an undesired feature. Corrosion induced by contact with biodiesel both reduces the life of metal parts and deteriorates the fuel properties, hence adversely affects engine performance. Therefore, the corrosive characteristics of biodiesel are very important for long term durability of engine components. In this study, we tried to investigate the corrosive effects of biodiesel and blends on engine parts by evaluating and comparing test results from earlier studies for different periods at different temperatures with different biodiesel fuels. Remedial measures to inhibit or mitigate corrosive effects of biodiesel by using additives are also tackled. Fosil yakıt kaynaklarının hızla tüketilmesi ve enerji ihtiyacının karşılanmasında dışa bağımlılık kaygısı, alternatif yakıt araştırmalarına yol açmıştır. Transesterifikasyon yoluyla bitkisel yağ ve hayvansal yağ gibi birçok yenilenebilir kaynağından elde edilebilen biyodizel, otomobiller için, özellikle çevre dostu olmak için en çekici alternatif yakıttır. Ancak bazı eksiler de var. Biyodizelde su ve serbest yağ asitleri varlığı onu petrol türevi dizelden daha korozif yapar ve bu istenmeyen bir özelliktir. Biyodizel ile temastan kaynaklanan korozyon hem metal parçaların ömrünü azaltır hem de yakıt özelliklerini kötüleştirir ve bu nedenle motor performansını olumsuz olarak etkiler. Bu nedenle, biyodizelin korozif özellikleri, motor bileşenlerinin uzun süreli dayanıklılığı için çok önemlidir. Bu çalışmada, farklı biyodizel yakıtlarıyla farklı sıcaklıklarda farklı dönemler için önceki çalışmaların test sonuçlarını değerlendirerek ve karşılaştırarak biyodizel ve harmanların motor parçaları üzerindeki korozif etkileri araştırılmıştır. Katkı maddeleri kullanarak biyodizelin korozif etkilerini önlemek veya azaltmak için düzeltici önlemler de ele alınmaktadır.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.