Mass Loss Of Specimens Research Articles

Ultra-low-temperature process effects on microscale abrasion of tool steel AISI D2

ABSTRACTUltra-low-temperature process treatments could raise tool steel wear resistance through microstructural change that occurs on the material, enhancing, that way, tools and dies lifetime. To investigate the tool steel wear resistance impact, micro-abrasive wear tests were carried out and an analysis based on the Archard’s law was considered, evaluating specimen mass loss by laser interferometry. Micro-hardness, X-ray diffractometry, scanning and optical microscopy and carbides quantitative evaluation were carried out aiming to material characterisation. Results demonstrated a micro-hardness improvement, ranging from 0.9–4.7% for the cryogenically treated specimens, when compared to the bulk material. This effect is related, mainly, to the retained austenite transformation and to the increase of fine secondary carbides dispersed amount in the martensitic matrixes cryogenically treated.

Durability performance of geopolymer cement based on fly ash and calcium aluminate cement in mild concentration acid solutions

The present work evaluates 2-year durability performance of geopolymer cement (GC) mortar derived from a blend of low calcium fly ash and calcium aluminate cement in hydrochloric and sulfuric acid solutions of mild concentration (pH 3). The dry binary blend was activated by a solution of sodium hydroxide and liquid sodium silicate and the GC mortar specimens were cured hydrothermally. At different time intervals of acid attack, the compressive strength and mass loss of specimens were measured and complementary studies on compositional and microstructural changes were performed using X-ray diffractometry, Fourier transform infrared spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy. The results revealed a superior durability performance for GC mortar especially in hydrochloric acid, compared to Portland and high alumina cement mortars used as reference. In addition, all the three cements showed a considerably higher degree of deterioration in exposure to sulfuric acid than in hydrochloric acid.

Influence of niobium and molybdenum addition on microstructure and wear behavior of laser-borided layers produced on Nimonic 80A-alloy

Abstract Laser alloying was used for production of thick layers on surface of Nimonic 80A-alloy. For laser surface modification, three types of pre-coated pastes were applied: with amorphous boron, with amorphous boron and molybdenum as well as with amorphous boron and niobium. The microstructure, hardness and wear resistance of produced layers were studied in details. The presence of different types of borides in re-melted zone depended on the paste composition and caused an increase in hardness up to about HV 1000. The wear resistance was evaluated by calculation of mass wear intensity factor Imw and relative mass loss of specimen and counter-specimen. The wear behavior of the tested frictional pairs was determined by 3D interference microscopy, scanning electron microscopy equipped with EDS microanalyzer. The significant increase in abrasive wear resistance was observed in comparison to untreated Nimonic 80A-alloy. The lowest mass loss intensity factor was characteristic of laser-alloyed Nimonic 80A-alloy with boron and niobium (Imw=1.234 mg/(cm2·h)). Laser alloyed-layers indicated abrasive wear mechanism with clearly visible grooves. Laser alloying with boron and niobium resulted in the additional oxidative wear mechanism. In this case, EDS patterns revealed presence of oxygen on the worn surface of specimen.

Effect of specimen bed on the material removal due to the repetitive single ball impacts

Specimen wear due to the repetitive single ball impact is investigated experimentally by a drop test machine. Effect of the impact energy, incidence angle and bed material is studied. Specimen mass loss is measured after 1000 impacts. The crater dimension on the specimen surface is measured to indicate its correlation with the wear variation. Results show that the rubber bed has the undeniable positive role in decrement of the wear due to impact comparing with the steel bed. A relation between the energies which give the same wear, in both cases of the rubber and steel bed, is extracted. Results can be helpful in designing the appropriate bed where the medium and high energy impacts encouraged.

Experimental Investigation on Mechanical and Durability Properties of Concrete with Plastic Waste

Industrial activities in India are associated with significant amounts of non – biodegradable solid waste and plastic waste. Plastic waste being prominent which is rarely recycled with as much as 40% left in landfill. Plastic waste is causing environmental pollution which is a major problem in the present era as the usage of plastic is growing day by day and it takes hundreds of years for plastic material to degrade. The plastic if burnt releases many toxic gases, which are very dangerous for health. So, there is an urgent need to recycle plastic waste so as to reduce the environmental impact. One possible way to minimize the plastic waste is to use plastic waste in concrete industry. Environmental concerns arising from the over dredging of sand have led to restriction on its extraction across India, a suitable environmental friendly alternative to sand must be found to match the huge demand in the concrete construction industry. To tackle both the issues plastic waste can be used in the concrete as the replacement of fine aggregate in known proportions. In this research work the fine aggregate has been replaced by two types of plastic waste, one is Low Density Polyethylene (LDPE) and second one is Polypropylene (PP) in varying proportions to find out the optimum content of plastic waste. The optimum content of plastic waste was determined by conducting tests on mechanical and durability properties. The mechanical test results shown that LDPE and PP plastic waste can be used in concrete mixtures up to 5% replacement level with fine aggregate. For this replacement level the durability property – Sulphate attack resistance was determined, results demonstrate the mass loss of specimens and compressive strength.

The role of microstructure and microchemistry on intergranular corrosion of aluminium alloy AA7085-T7452

The intergranular corrosion (IGC) of an AA7085-T7452 aluminium alloy forging was determined via ASTM G110 exposure, and rationalised with electron backscattered diffraction and transmission electron microscopy. The alloy microstructure, microchemistry and IGC propensity varied depending on the location within the forging, and thus quarter (t/4) and mid (t/2) thicknesses of the forging were explored herein. The number of IGC fissures and mass loss of specimens was lower in the t/2 position, as a result of higher Cu content in grain boundary precipitates, η-phase, Mg(Cux=0.08–0.32Zn1-x)y=1.4–2.8 and (Zn, Cu)-rich η-phase, Mg(Cux=0.2–0.54Zn1-x)y=4.4–8.5 in the t/2 position, whilst the t/4 position contained η-phase, Mg(Cux=0.09–0.31Zn1-x)y=1.7–2.3 and Zn-rich η-phase, Mg(Cux=0.05–0.12Zn1-x)y=4.4–4.5.

Accelerated Corrosion Analysis of AlSi10Mg Alloy Manufactured by Selective Laser Melting (SLM)

The Selective Laser Melting (SLM) technology uses metal powders as building material which is melted and welded together using a high-power laser in order to obtain quick configuration of complex parts, most often for testing them. Another advantage of this method is the fact that allows obtaining any 3D geometry of the parts, even parts that cannot be processed through conventional manufacturing procedures. In this work were performed a number of tests for accelerated corrosion of AlSi10Mg alloy specimens in order to determine their mean life in the conditions of their use in a high salinity environment. For specimens, optical analysis was used the SEM microscope which has the advantage of obtaining an enlarged image of the investigated objects without processing. Following these analyses, it has been determined the mass loss of specimens due to corrosion.

Influence of tribo-magnetization on wear debris trapping processes of textured dimples

Abstract The mechanism of attachment of wear debris to textured dimples was investigated experimentally. Textured dimples were fabricated on the surface of medium carbon steel specimen with drilling method. Reciprocating ball on disc sliding wear experiments were carried out. The dimples trapped with wear debris and worn surfaces were observed with microscope. Tribo-magnetization of wear debris was employed to explain the attachment of debris in dimples. The size of wear debris and magnetic flux density of worn surfaces were measured. Wear experiments processes were also carried out under degaussing conditions. The experimental results show that tribo-magnetization causes the phenomena of attachment and bridging of wear debris to edge of textured dimples. By applying degaussing method, attachment of wear debris within textured dimples can be reduced. For comparison, coefficients of friction, wear mass loss of specimens and wear volume loss of mating balls were measured under both conditions of non-degaussing and degaussing. Degaussing can be beneficial to improve the capacity of trapping wear debris of textured dimples for ferromagnetic materials, and to improve the wear resistance of dimple textured specimen.

Physico-Mechanical Properties and Durability Aspects of Alkali-Activated Calcareous Fly Ash/Slag Mortars

In this paper, the physico-mechanical properties of alkali-activated mortars (CF/S) containing calcareous fly ash (CF) from the combustion of lignite and ladle furnace slag (S) from the steelmaking process as binders as well as sand and glass cullet as inert material have been studied. The constituents were mixed with the alkaline activator (NaOH:Na2SiO3 was 1:1). The binders and aggregates were used in a ratio 1:3 while a part of sand was replaced by glass aggregates (60%). The specimens (dimensions 40x40x160 mm) of alkali-activated mixtures CF/S: 100/0, 80/20 and 50/50 were cured at 25 °C for 2 days and then were placed in humid environment (95±5 % RH, 25 °C). Then the mechanical strength and porosity at 7-d, 28-d and 90-d age were measured. All of the CF/S specimens exhibited compressive strength around 15 MPa at 28 days. After the 28-d age the specimens of CF/S mortars were exposed to wetting/drying and freeze/thaw cycles to have an estimation of durability of alkali-activated CF/S mortars and compared to the Portland I42.5 cement mortars (PC) of high strength 43 MPa. Mass loss of specimens was measured by weighing them. The results showed that alkali-activated CF/S mortars appear to have similar or slight lower behavior to wetting/drying and freeze/thaw cycles compared to net cement mortars.

Joint experiments of cavitation jet: High-speed visualization and erosion test

Cavitation is a ubiquitous phenomenon in ocean engineering. In order to figure out the relationship between cavitation cloud and cavitation erosion, high-speed visualization and erosion test of cavitation jet were simultaneously performed. The temporal and spatial distributions of cavitation cloud was analyzed using Proper Orthogonal Decomposition (POD) and the morphology of eroded specimen was analyzed from both macroscopic and microcosmic perspectives. The results show that POD modes of side view images are able to estimate the maximum radial distribution of cavitation pits, while the energy fraction of the first POD mode can serve as an indicator of specimen mass loss. The intensity of cavitation erosion is decided by both the bubble concentration and collapse intensity at specimen surface. At a medium standoff distance, where collapse intensity and bubble concentration are well compromised, maximum cavitation erosion is achieved. The aggravation of cavitation erosion is the combined consequences of the growth of single cavitation pits and the connection of adjacent pits. These results suggest that the collapse of cavitation bubbles is a necessary, but not sufficient, condition for severe cavitation erosion. The findings are expected to improve the physical understanding of the relationship between cavitation phenomenon and cavitation damage.

High-rate erosion of Ti–6Al–4V ultrafine-grained titanium alloy obtained via intensive plastic torsional deformation

Testing results for Ti–6Al–4V ultrafine-grained titanium alloy obtained via intensive plastic torsional deformation (IPTD) are presented. To estimate the effect of IPTD treatment on the behavior of this material under erosion conditions, special experimental techniques were developed. The ultrafine-grained alloy was tested alongside with the traditional coarse-grained titanium alloy in an erosion wind tunnel in an air flow with corundum particles as an abrasive material. The erosion resistance of the material was estimated from the mass loss of specimens. Despite a considerable increase in the static strength characteristics, the nanostructured material did not demonstrate any increase in its erosion resistance in comparison with the initial alloy.

Abrasion erosion modeling in particulate flow

Solid particle erosion is of great importance to many industries including oil and gas production, drilling, process and transportation of minerals including oil sands. The particles that may cause erosion are of various sizes, shapes and hardnesses. These particles may impact the surface at various speeds and angles, and the influence of these parameters is characterized to some extent in the literature. Experimental and numerical studies have shown that when particles are transported by liquid (e.g. slurry transport in the pipe) or dense gas, the particle impact angles are very low. The impact angles in these cases are sometimes less than the smallest value that can be obtained in a direct impingement erosion test in gas. In this work, the mechanistic erosion equation developed previously is extended to near zero impact angles for sharp particles. The abrasion erosion equation is developed by introducing an initial penetration of the sharp particle in the equation of the motion. This initial penetration may be attributed to the sharp particle rotation and/or turbulent flow fluctuations of the carrier fluid near the wall. The empirical constants are obtained from submerged erosion experiments in liquid. The equation has been implemented in a commercially available Computational Fluid Dynamics (CFD) code (ANSYS FLUENT) to calculate erosion for a submerged impingement jet geometry, and the result is compared with the experiment. It is shown that by neglecting the abrasive term in the erosion equation, the specimen mass loss does not match the experimental measured mass loss. While by including the abrasive term, the total mass loss of the specimen agrees well with the experimental data. Moreover, the erosion pattern becomes closer to the experimentally measured pattern especially farther from the center of the highly eroded area where abrasive wear is expected to dominate.

Effect of cryogenic thermal cycling on SiC-modified C/C composites

The bonding strength, mechanical properties and high-temperature thermal shock resistance of C/C–SiC composites after undergoing simulated low earth orbit environment including cryogenic thermal cycles (CTCs) between 153 and 393 K for 200 times with high-vacuum state of 1.3 × 10−3 Pa were investigated. Results of the tests showed that, the bonding strength at coating/substrate interface monotonically decreased as the CTCs increased. After 100 CTCs, the flexural strength of C/C–SiC composites enhanced and the percentage of remaining strength was 102.60%, while, the mass loss of specimens decreased from 2.08 to 0.89% after thermal shock resistance test between 1773 K and room temperature for 15 times. Once CTCs exceed 100 times, the mass loss increased, the flexural strength reduced and remained only 87.40% of initial strength after 200 CTCs. The fractural behaviour of CTCs-treated modified composites exhibited typical brittle mode. A model based on the evolution of the residual thermal stress after CTCs treatment was proposed to explain the oxidation failure mechanism of C/C–SiC specimens.

Corrosion Resistance of Nitric Acid Passivated Cr-Ni-Mo Stainless Steel

Austenitic stainless steels are considered materials with excellent corrosion resistance, and with acceptable mechanical properties. Therefore they are recommended for various constructional, industrial and biomedical applications. However they are prone to the pitting corrosion in aggressive chloride environments. The aim of this study is to evaluate the corrosion resistance of AISI 316Ti stainless steel with nitric acid passivated surface at the temperature range 22 – 80 °C in 1M acidic chloride solution. Evaluation of the corrosion resistance is based on the results of exposition immersion tests (visual and microscopic observation of attacked surfaces, mass losses of specimens) and the results of the electrochemical impedance spectroscopy (EIS) tests.

Corrosion resistance of Cr-Ni-Mo Stainless Steel in Chloride and Fluoride Containing Environment

Austenitic stainless steels are widely used for various biomedical applications because of their biocompatibility, high resistance to uniform corrosion and suitable mechanical properties. However, they are prone to local corrosion in aggressive halides environments. This article focuses on the effect of fluoride added to physiological saline solution (0.05 % NaF resp. 0.5 % NaF + 0.9 % NaCl solution) and on the effect of fluoride containing mouthwash (0.05 % NaF) on corrosion resistance of AISI 316L surgical steel. Evaluation is based on results of 42-days exposition immersion tests performed at the temperature of 37 °C (REM observation of attacked surfaces, mass losses of specimens) and on the results of the electrochemical cyclic potentiodynamic polarisation tests performed in the same solutions at the same temperature.

Moisture and decay resistance and reaction to fire properties of self-binding fibreboard made from steam-exploded grey alder wood

A study of self-binding fibreboards pressed without synthetic adhesives is reported. The board samples of steam-exploded grey alder (Alnus incana L. Moench) particles hot-pressed under a variety of conditions including moisture content of the mat (8% and 12%), temperature (150°C, 160°C, 170°C and 180°C) and pressure (0.2–8 MPa) are tested for moisture resistance (standard EN 1087-1), decay resistance (standard ENV 12038) and reaction to fire performance (ISO 5660-1). The moisture resistance of the board samples is found to satisfy the standard EN 622-5 for load-bearing medium-density fibreboard for use in humid conditions (MDF.HLS). The tested board samples are not fully resistant to the Trametes versicolor fungus, the mass loss of specimens exceeding 3%. Reaction to fire performance of the self-binding board evaluated by the average rate of heat emission being by about 25% higher is worse compared with MDF.HLS.

Effect of drying-wetting cycles on leaching behavior of cement solidified lead-contaminated soil

Lead contaminated soil was treated by different concentration of ordinary Portland cement (OPC). Solidified cylindrical samples were dried at 40°C in oven for 48h subsequent to 24h of immersing in different solution for one drying-wetting. 10 cycles were conducted on specimens. The changes in mass loss of specimens, as well as leaching concentration and pH of filtered leachates were studied after each cycle. Results indicated that drying-wetting cycles could accelerate the leaching and deterioration of solidified specimens. The cumulative leached lead with acetic acid (pH=2.88) in this study was 109, 83 and 71mg respectively for solidified specimens of cement-to-dry soil (C/Sd) ratios 0.2, 0.3 and 0.4, compared to 37, 30, and 25mg for a semi-dynamic leaching test. With the increase of cycle times, the cumulative mass loss of specimens increased linearly, but pH of filtered leachates decreased. The leachability and deterioration of solidified specimens increased with acidity of solution. Increases of C/Sd clearly reduced the leachability and deterioration behavior.

Accurate Electrochemical Measurement of Magnesium Corrosion Rates; a Combined Impedance, Mass-Loss and Hydrogen Collection Study

Experiments were conducted to enable the simultaneous measurement of electrochemical impedance and collection of hydrogen gas during the corrosion of pure magnesium in NaCl solutions. These results were then assessed along with the attendant specimen mass loss, providing three unique measures of magnesium corrosion for the same specimen. It was determined that analysis of impedance data, while accounting for a physically justified inductive response at low frequencies, enabled the determination of the polarization resistance, RP at the zero frequency limit. The determination of RP, as evaluated herein from electrochemical testing, provided excellent correlation to the mass loss and volume of hydrogen collected. This finding is elaborated in a broader discussion that critically addresses previous studies which have utilized the impedance behavior of magnesium and which claim electrochemical tests may underestimate Mg corrosion when attempting to use a charge transfer resistance at intermediate frequencies.

Fabrication and behaviour of Al–Si/SiC composite in cavitation conditions

Aluminium matrix composite (AMC) specimens were prepared using the compocasting technique. The reinforcements used were silicon carbide (SiC) particles with an average size of 30 μm. The influence of reinforced ratio of 10 wt-%SiC on cavitation behaviour was examined. The cavitation resistance of an AMC with SiC (AlSi/SiC) was evaluated using an ultrasonically induced cavitation test method. The mass loss of specimens was measured by an analytical method. The morphology of the damaged surface of tested composite was examined using scanning electron microscopy (SEM). It is shown that the cavitation rate of an AMC with SiC is almost the same as the CA6NM stainless steel, which is largely used in the production of hydraulic machinery components. Because the results show that the composites exhibited very good resistance to the cavitation erosion, this material can be successfully used under conditions where the cavitation resistance is needed.

The effects of pozzolanic binders and polypropylene fibers on durability of SCC to magnesium sulfate attack

The effects of various pozzolanic binders such as silica fume, metakaoline and zeolite on self consolidating concrete (SCC) durability in magnesium sulfate environment were studied. Change in compressive strength, mass and dimensions of concrete specimens were measured after 6 and 9months immersion in 5% and 10% magnesium sulfate solutions. In this study the effect of polypropylene fibers together with pozzolanic binders on SCC durability in sulfate environment were also investigated. To contrast the use of pozzolanic binders on internal characteristics of concrete, samples were observed by scanning electron microscopy (SEM). To evaluate the intensity of elements in paste compositions, energy-dispersive X-ray spectroscopy (EDX) tests were accomplished. Test results showed that metakaoline and zeolite have better effects than silica fume on durability of SCC to magnesium sulfate attack. The least expansion occurred in zeolite SCC. Applying polypropylene fibers reduced mass loss in specimens but not much effect was observed on volume expansion of specimens.