Advanced Materials and Processes Research Institute
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Corrosion and sulphate ion reduction studies on Ni and Pt surfaces in with and without V 2 O 5 in ( Li, Na,K) 2 so 4 melt
No full textIn the present investigation corrosion and sulphate ion reduction on the nickel and platinum surfaces, respectively have been studied in (Li,Na,K)2SO4 melt in the presence and absence of V2O5 at 550 °C. The corrosion or oxidation rate of nickel was derived by Tafel extrapolation method while cyclic voltammetry measurement was employed for the determination of electrochemical behaviour of sulphate ion. According to result obtained, corrosion of nickel increases very fast after the addition of V2O5 and becomes more than two orders of magnitude higher in the presence of 3% V2O5 in the melt. Three well defined cathodic peaks related to vanadate ion reduction, were clearly observed in the cyclovoltammogram obtained on the Pt surfaces in presence of V2O5 in the melt. Observation of three reduction peaks could be due to subsequent reduction of vanadate ion to its lower oxidation state. From the results, a conclusion has been drawn that a strong ability of vanadium to reduce in its lower oxidation state by consuming electrons released by sulphate ion oxidation, is mainly responsible for enhancement of corrosion or oxidation of the nickel in the sulphates melt
Effect of pyrophyllite additions on sintering characteristics of fly ash based ceramic wall tiles.
No full textThe sintering characteristics of fly ash-pyrophyllite mixes containing 0-100 wt-% sericitic pyrophyllite have been studied, using 10 wt-% sodium hexametaphosphate as a binding agent and a firing temperature of 950°C. Increasing pyrophyllite content has been observed to increase the impact strength and apparent density and decrease the water absorption of sintered tile samples. Moreover, the presence of pyrophyllite imparted improved thermal shock resistance to the wall tile samples
Role of PET in improving wear properties of PP in dry sliding\ud condition
No full textThe sliding wear of isotactic polypropylene (PP), polyethylene terephthalate (PET) and theirblends was evaluated as a function of applied pressure and composition against a stainless steel counter face in dry condition. Wear rate decreases with the addition of PET in the blend. The wear was observed in two stages, the moderate wear and high wear while increasing the applied pressure on test samples. The addition of PET in PP helps in increasing the limit of moderate wear towards the high-pressure side. Microstructure and worn surfaces of samples were observed by scanning electron microscope. The wear phenomenon has\ud
been discussed based on wear losses and worn surfaces
Dynamic Mechanical Behavior of LLDPE Composites Reinforced with Kevlar Fibers/Short Glass Fibers
No full textKevlar fibers (DuPont) and glass fibers have been used to reinforce linear lowdensity polyethylene (LLDPE) by using an elastic melt extruder and the compression molding technique. The impact behavior of hybrid composites of different compositions is compared and has been explained on the basis of volume fraction of fibers. The addition of glass fibers decreases the Izod impact strength of LLDPE. The Izod impact strength of the composite increses when glass fibers are replaced by Kevlar fibers. Dynamic mechanical α-relaxation is studied and the effect of variation of fiber composition on the relaxation is reported in the temperature range from −50°C to 150°C at 1 Hz frequency. The α-relaxation shifts towards the higher temperature side on addition of fibers in LLDPE. The addition of fibers increases the storage modulus, E′, of LLDPE. The hybridization of Kevlar and glass fibers helps in desiging composites with a desirable combination of impact strength and modulus. At the low temperature region, E′ increases significantly with glass fibers as compared to that noted with the addition of Kevlar fibers. The α-transition temperature of composites increases significantly with Kevlar fibers as compared to that observed with addition of glass fibers
Age hardening of Al 201-alloy and 2014-SiC composites
No full textDetails the synthesis of aluminum 2014-alloy and 2014-10% SiC particle composites by the liquid metallurgy route. Preparation of the composite by melting the alloys in a gas fired furnace in a graphite crucible; Determination of the hardness of the aged samples; Use of a tungsten carbibe ball indentor to produce the indentation; Comparison of the hardness of the alloy and composite
Abrasive wear behaviour of high carbon steel: effects of microstructure and experimental parameters and correlation with mechanical properties.
No full textThis investigation deals with the observations made towards understanding the role of interlamellar spacing on the high-stress abrasive wear behaviour of a high carbon steel. The samples revealed near-eutectoid (pearlitic) structure. The interlamellar spacing was varied by altering the austenitization temperature. Abrasion tests were conducted over a range of applied load, sliding speed,travel distance and abrasive size. Mechanical properties such as hardness, impact toughness and tensile strength, yield strength and\ud
elongation at fracture of the samples were also evaluated. The nature of dependence of abrasive wear rate and the measured mechanical properties on material related factors like interlamellar spacing of the samples has been analyzed. The study indicates that the wear rate does not follow a Hall-Petch relationship with the interlamellar spacing of the samples unlike hardness and yield strength. An analysis of the influence of abrasion test parameters suggested the wear rate to increase sharply with load initially. This\ud
was followed by a lower rate of increase or even a reduction in wear rate at higher loads depending on the interlamellar spacing of the samples. Increasing abrasive size caused the wear rate to practically remain unaffected initially. This was followed by a sharp increase in wear rate beyond a critical abrasive size. Increasing speed led to higher wear rates upto a critical sliding speed beyond\ud
which the wear rate decreased with a further increase in speed. The varying nature of influence of interlamellar spacing on mechanical properties and interlamellar spacing and abrasion test parameters on the wear response of the samples has been discussed in terms of wear-induced subsurface work hardening/deformation of the specimens, deteriorating cutting efficiency of the\ud
abrasive particles, stability of the deformed (transfer) layer in the near vicinity of the wear surface during abrasion and hardening of ferrite in the (eutectoid) cementite/ferrite (pearlite) mixture in the steel prior to testing
The effect of different metallic counterface materials and different surface treatments on the wear and friction of polymide 66 and its composite in rolling-sliding contact.
No full textThe effect of different metallic counterface materials and different surface treatments on the tribological \ud
behaviour of polymer and polymer composite under unlubricated, non-conformal and rolling-sliding \ud
contact has been investigated. The most widely used polymer materials - unreinforced polyamide 66 and \ud
its composite (RFL4036) – were tested. The metallic materials include aluminium, brass and steel and \ud
the surface treatments include Tufftride** treated (known as nitrocarbonising) and magnesium \ud
phosphate treated, etc. Tests were conducted over a range of slip ratios at a fixed load of 300 N, 1000 \ud
rpm rotational speed using a twin-disc test rig. The experimental results showed that the polyamide \ud
composite exhibited less friction and wear than the unreinforced polyamide 66 when running against \ud
steel and aluminium counterfaces. However, when tested against brass, polyamide 66 exhibited lower \ud
wear than the composite. The surface treatment of steel has a significant effect on the coefficient of \ud
friction and the wear rate, as well as on the tribological mechanism, of polyamide 66 composites. It has \ud
been observed that a thin film on the contact surface plays a dominant role in reducing the wear and \ud
friction of the composite and in suppressing the transverse cracks. This study clearly indicates that both \ud
the characteristics of the different counterface metallic materials and the surface treatment greatly \ud
control the wear behaviour of polyamide 66 and its composite. \u
Effect of sillimanite particle Reinforcement on the dry sliding wears behavior of Aluminum alloy composite.
No full textThe effect of sillimanite reinforcement on the dry sliding wear behaviour of aluminium silicon alloy (BS LM6) composite was investigated using a pin-on-disc sliding wear test machine. The composite specimens were prepared using the liquid metallurgy technique and 10 wt-% of sillimanite particles were incorporated in the matrix alloy. Sliding wear tests were conducted at applied pressures between 0.2 and 1.6 MPa and speeds of 1.89, 3.96 and 5.55 m s-1. The matrix alloy was also prepared and tested under identical conditions in order to enable comparison. It was observed that the sillimanite reinforced composite exhibited a lower wear rate than the matrix alloy. Increase in applied load increased the wear rate while increase in speed exhibited the reverse effect. The seizure pressure of the composite was significantly higher than that of the matrix alloy. The temperature rise near the contacting surface and the coefficient of friction were less in the composite than in the matrix alloy. SEM micrographs of the worn surface and subsurface were used to predict the nature of the wear mechanism
Pentagonal and trigonal quasilattices and their approximants
No full textThe Strip Projection Method is used to generate pentagonal and trigonal 2-dimensional quasilattices as rational approximants to the icosahedral quasilattice. Further, 3-dimensionally periodic structures are generated as rational approximants to these 2-dimensional quasilattices. A simplified approach based on uniform distortions of perpendicular space is put forth for the analyses
The "fish-hook" phenomenon in centrifugal separation of fine particles.
No full textThe literature on “fish-hook” in hydrocyclones is growing and so an attempt has been made to provide a mechanistic argument supporting its occurrence in all centrifugal separators.\u