WEAR PROPERTIES OF FE-CUC BASED MATERIALS PRODUCED BY POWDER METALURGY
In this study, Fe-Cu-C based compact in various weight ratios of iron, copper and graphite additions to starting powder have been produced by powder metallurgy. The effects of copper and graphite additions and sliding speeds during wear tests on wear behaviours were investigated. In this study, wear tests were carried out by using pin on disc sliding wear machine with the sliding speeds of 1, 1,5 and 2 msn at the constant loads of 20N. 2000 m total sliding distance was selected. Scanning Electron Microscopy (SEM) studies were carried out on the cross section of the compacts. Worn surfaces of the samples after tests were also examined by using scanning electron microscope and energy dispersive spectroscopy (EDS) analyses. The results obtained from experimental work shows that addition of copper and graphite and sliding speed effect on wear behaviours of sintered alloyed steel materials.
Dry sliding friction and wear characteristics of Fe–C–Cu alloy containing molybdenum di sulphide
Abstract Sintered steels find increasing application as bearings and gears due to economical and technical reasons. Materials used for making these machine elements need to have high strength, good wear resistance and low coefficient of friction. An attempt is made to develop molybdenum di sulphide added iron–copper–carbon sintered steels using simple single stage compaction and sintering elemental powders. Friction and wear characteristics of the developed materials were evaluated using cylindrical specimens in a pin-on-disc sliding apparatus. Addition of molybdenum di sulphide increases the compressibility and increases the part density. Strength and hardness of the molybdenum di sulphide added compositions are better than the base composition. Addition of the 3% molybdenum di sulphide is found to be beneficial in improving friction and wear characteristics. Higher amount of brittle phases in the 5% molybdenum di sulphide added sample contributes to the reduction in the wear resistance.
The first ground cricket (Orthoptera: Trigonidiidae: Nemobiinae) from mid-Cretaceous Burmese amber
Abstract A new genus and species, Birmaninemobius hirsutus gen. et sp. nov., is described on the basis of a well-preserved orthopteran specimen in mid-Cretaceous Burmese amber and attributed to the subfamily Nemobiinae (ground crickets) of the family Trigonidiidae (Grylloidea). As the first record of Nemobiinae from mid-Cretaceous Burmese amber, this new taxon not only provides novel morphological diversity in ground crickets but also indicates that the ground crickets lived in Burma (Tethyan islands) as early as the mid-Cretaceous.