Heat-treated Counterparts Research Articles

Improved Corrosion Resistance on Selective Laser Melting Produced Ti-5Cu Alloy after Heat Treatment.

A Ti-5Cu alloy produced by selective laser melting exhibits a nonuniform Ti2Cu phase structure, which contains a small amount of α' phase in melt pool boundaries thereby resulting in reduced corrosion resistance. The heat-treatment process proposed in this work eliminates the deleterious effect of α' phase and the Ti2Cu phase is refined using different cooling rates, which improves the corrosion resistance. The electrochemical results indicate that the heat-treated Ti-5Cu samples have similar corrosion behavior to pure CP-Ti. A slower cooling rate produces a larger spacing between the Ti2Cu phases in the microstructure of the sample, resulting in higher corrosion resistance. The corrosion behavior of SLM-produced Ti-5Cu and heat-treated counterparts with different microstructure are detailed discussed.

Isothermal fatigue behaviours of Mg-12Gd-3Y-0.5Zr magnesium alloy at elevated temperatures

Isothermal fatigue tests were carred out on Mg-12Gd-3Y-0.5Zr magnesium alloy and its heat-treated counterpart at different temperatures. The exprimental results shows that isothermal fatigue strength of two alloys decrease very slowly with increasing temperature up to 200°C. The ultimate tensile strength of heattreated Mg-12Gd-3Y-0.5Zr is slight lower than that of as-rolled counterpart, however, the fatigue strength of heat-treated alloy is higher.

Interfacial and foaming characterisation of mixed protein-starch particle systems for food-foam applications

This work presents mixed protein-starch systems as effective foaming agents and stabilisers. The starch size and hydrophobicity play a dominant role in determining the levels of synergy observed. Egg White Protein (EWP) and Pea Protein Isolate (PPI) were selected at two concentrations (0.5, 1 wt. %) along with three starch species of concentrations between 0.5, 1, 3 & 5wt. %. Two commercial OSA-modified starches are compared to a native granule and its heat-treated counter part. The system's effectiveness to incorporate air (overrun) as well as its capacity to hold structure (half life) is evaluated. starch's physical properties (contact angle and size) and their effect on the nature of the Air/Water (A/W) interface (interfacial dilatation rheology, surface tension) are also explored. The effect of protein species as well as starch size and hydrophobicity on foam stability is determined and discussed. The study demonstrates that addition of OSA modified starch (0–5wt%) to (EWP) foams can enhance foam stability by up to 1200% without compromising the foaming capacity, mainly due to a hypothesised exclusion volume effect. Where as the larger heat-treated starch granule is found to increase stability of wet foams by 800%, through a combination of mechanisms.

Effects of ultraviolet light (UV-C) and heat treatment on the quality of fresh-cut Chokanan mango and Josephine pineapple.

The effects of ultraviolet (UV-C) and medium heat (70°C) treatments on the quality of fresh-cut Chokanan mango and Josephine pineapple were investigated. Quality attributes included physicochemical properties (pH, titratable acidity, and total soluble solids), ascorbic acid content (vitamin C), antioxidant activity, as well as microbial inactivation. Consumers' acceptance was also investigated through sensory evaluation of the attributes (appearance, texture, aroma and taste). Furthermore, shelf-life study of samples stored at 4 ± 1°C was conducted for 15 d. The fresh-cut fruits were exposed to UV-C for 0, 15, 30, and 60 min while heat treatments were carried out at 70°C for 0, 5, 10 and 20 min. Both UV-C and medium heat treatments resulted in no significant changes to the physicochemical attributes of both fruits. The ascorbic acid content of UV-C treated fruits was unaffected; however, medium heat treatment resulted in deterioration of ascorbic acids in both fruits. The antioxidants were enhanced with UV-C treatment which could prove invaluable to consumers. Heat treatments on the other hand resulted in decreased antioxidant activities. Microbial count in both fruits was significantly reduced by both treatments. The shelf life of the fresh-cut fruits were also successfully extended to a maximum of 15 d following treatments. As for consumers' acceptance, UV-C treated fruits were the most accepted as compared to their heat-treated counterparts. The results obtained through this study support the use of UV-C treatment for better retention of quality, effective microbial inactivation and enhancement of health promoting compounds for the benefit of consumers.

Nanofiber Fuel Cell Electrodes I. Fabrication and Performance with Commercial Pt/C Catalysts

Nanofiber electrodes prepared with three different commercial Pt/C catalysts and 1100 EW Nafion® binder were fabricated by electrospinning. The electrodes were further processed into membrane-electrode-assemblies (MEAs) using Nafion 211 as the membrane material. MEAs were evaluated for catalyst activity and power output in a hydrogen/air fuel cell at 80oC. Tanaka Kikinzoku Kogyo (TKK) TEC10E50E (46.1% Pt on Ketjen Black) was more electrochemically active and produced slightly more power than its heat-treated counterpart, TKK TEC10E50E-HT (50.5% Pt on Ketjen Black), and Johnson Matthey HiSpec 4000 catalyst (40% Pt on Vulcan carbon). The nanofiber cathodes were compared to MEAs with standard non-structured gas diffusion electrodes (GDEs) containing the same catalysts, and in all cases, the electrospun fibers generated more power. For example, with a Pt loading of 0.10 mg/cm2, the electrospun TKK TEC10E50E generated 470 mW/cm2 at a 0.65 V vs. 349 mW/cm2 for the GDE-based MEA, an improvement of 35%. The effect of nanofiber composition (the ratio of Pt/C to Nafion) and the effect of fiber diameter on power output were also investigated. In general, such changes had a little or no impact on performance and all the electrospun mats tested yielded MEAs that produced very high power.

Experimental investigation on the indentation hardness of precursor derived Si–B–C–N ceramics

The elasto-plastic response of the precursor derived Si–B–C–N ceramics upon contact loading was determined by depth sensing nanoindentation technique. The indentation response of as-thermolyzed Si–B–C–N ceramic was compared with the heat-treated counterpart. The as-thermolyzed ceramic was X-ray amorphous and the heat-treated ceramic was phase separated and crystallized. The hardness and reduced elastic modulus values of the as-thermolyzed ceramic were ∼16 GPa and ∼172 GPa, respectively. The reduction in hardness to ∼9 GPa in the heat-treated ceramic was attributed to phase separation and crystallization of SiC and Si 3 N 4 . Furthermore, high elastic recovery with a plastic work ratio of ∼0.3 was observed and ascribed to volume controlled deformation mechanism .

Comparison of antifungal activities of scallop shell, oyster shell and their pyrolyzed products

Waste shells create several serious problems, however, only parts of them are being utilized now. Therefore, the ideal solution would be to convert the waste shells into a product that is both environmentally beneficial and economically viable. Scallop and oyster shells were exposed to heat treatment at 1050°C. SEM and XRD analysis results showed that the resultant powder turned completely into CaO after the treatment. The antifungal activities of non-treated and heat-treated scallop and oyster shell powder slurry were investigated. Non- treated oyster shell powder exhibited a significant antifungal activity at 25,000ppm. Its antifungal activities against Physalospora piricola Nose (P. piricola) and Rhizoctonia solani Kühn (R. solany) were even up to 100%. Moreover, increasing culture time did not alter the antifungal activities. Heat-treated scallop and oyster shell powder exhibited obvious antifungal activity at 500ppm, at which concentration 100% inhibition of R. solany was observed. The possible antifungal mechanism of the oyster shell and its heat-treated counterpart was studied using R. solani Kuhn as model. The results illustrated that oyster shell is able to affect the membrane permeability of the fungus. The above-mentioned results showed that it is possible for oyster shell to be an agriculture fungicide.

In-vitro assessment of the forces generated by lingual fixed retainers

The aim of this article was to assess the effect of wire adaptation on the lingual surfaces of mandibular anterior teeth with 3 types of lingual retainers on the development of vertical and labiolingual forces. Ten retainers (canine to canine) were constructed from each of the following wires: Wildcat 0.0195-in heat-treated 3-strand twist-flex wire (GAC, Bohemia, NY); Penta-one 0.0215-in 6-strand as received; and Penta-one 0.0215-in 6-strand after heat treatment at 350°C for 4 minutes (both, Masel Orthodontics, Carlsbad, Calif). The retainers were bonded on each tooth of an acrylic resin model, and the model was installed in the Orthodontic Measurement and Simulation System. The vertical and labiolingual forces generated were measured for wire displacements up to 0.2 mm in 0.02-mm increments. Wire displacement of 0.2 mm exerted forces as high as 1 N on the teeth. In the vertical direction, the highest force levels were recorded for the as-received Penta-one 0.0215-in and the lowest from its heat-treated counterpart. In the horizontal plane, the as-received Penta-one 0.0215-in exerted the highest forces. The forces recorded from the lingual retainer wires during 0.2-mm simulated intrusion-extrusion and buccal-lingual movements might generate high forces that exceed 1 N and be large enough to produce unwanted tooth movement during retention. The only significant determinant of the generated forces was the amount of wire displacement and not the type of wire used in this study.

Comparison of pressure treatment and heat treatment of skim milk with added starch on subsequent acid gelation of milk

Skim milk with added starch (waxy rice starch or potato starch at levels of 0–1.5 g/100 g) was either pressure-treated (500 MPa, 20 °C, 30 min) or heat-treated (80 °C, 30 min) and subsequently acidified (using glucono-δ-lactone) to form acid milk gels. In the second part of the study, the pH of the skim milk samples was adjusted from the natural condition (pH 6.64) to pH 6.5, 6.6 or 6.9 before the pressure or heat treatment and re-adjusted back to pH 6.64 after the respective treatment. The rheological properties of the samples during acidification and of the final acid gels were studied. The storage modulus, G′, of the final acid milk gels increased as more waxy rice starch was added to milk before pressure or heat treatment. However, acid milk gels made from pressure-treated milk with added potato starch did not show significant changes in the G′ of the final acid gels whereas those made from the heat-treated counterparts showed a marked increase in the final G′ as the potato starch level increased. Waxy rice starch was gelatinised in milk by both pressure treatment and heat treatment whereas potato starch was gelatinised by heat treatment only. Increasing the pH of milk before pressure or heat treatment increased the final G′ of the acid milk gel produced on subsequent acidification of the milk and the final G′ was increased further by the addition of waxy rice starch before the pressure or heat treatment.

Impact wear behavior of laser hardened hypoeutectoid 2Cr13 martensite stainless steel

Impact assessment for laser hardened hypoeutectoid 2Cr13 martensite stainless steel was carried out on a specifically developed ball-on-flat impact tester. Results showed better impact behavior of 2Cr13 surfaces treated by a continuous wave CO 2 laser than those under conventional heat treatment. Micro-hardness measurement demonstrated that the surface hardness of the laser treated specimens varied with the operation parameters of laser hardening. Scanning electron microscope (SEM) analysis and surface profile measurement suggested that the size of the impact wear scars of 2Cr13 specimens decreases with the increase of the surface hardness. EDX analysis showed that the oxidation resistance of the laser-hardened surfaces was relatively superior to their conventionally heat-treated counterparts. Compared with conventionally-treated 2Cr13 steel, the superior impact wear resistance of laser surface-processed steel was attributed both to grain refinement and to the higher martensite content near the surface that resulted from rapid cooling.

Effect of Heat Treatment on the Redox Properties of Iron Porphyrins Adsorbed on High Area Carbon in Acid Electrolytes: An in Situ Fe K-Edge X-ray Absorption Near-Edge Structure Study

Electronic aspects of an iron porphyrin, 5,10,15,20-tetrakis(4-methoxyphenyl)-21H,23H-porphine iron(III) chloride (FeTMPPCl) molecularly dispersed on a high area carbon black (Black Pearls 2000, BP) and then heat-treated (or thermally activated) at 800 °C in a flowing inert atmosphere, were investigated in situ in 1.0 M H3PO4 by Fe K-edge X-ray near-edge structure (XANES). Profound differences were observed between the ex situ (dry) XANES of electrodes incorporating FeTMPPCl/BP before and after heat treatment and, likewise, in the case of the thermally treated FeTMPPCl/BP before and after immersion of the electrodes in the electrolyte. Monotonic shifts in the absorption edge toward higher energies were observed for heat-treated FeTMPPCl/BP as the potential was increased over a range of over 1 V. The overall magnitude of the shift, ca. 2.5 eV, was virtually the same as that obtained with non-heat-treated (or intact) FeTMPPCl/BP, which occurred in a much narrower potential range, ca. 0.2 V. In contrast to the behavior observed for the intact adsorbed macrocycle, its heat-treated counterpart displayed no affinity for CO, indicating that, to the level of sensitivity of this technique, iron sites in the thermally activated material are quite different from those in the N4 environment of the intact macrocycle.

Effect of ion implantation on fatigue strength of martensite stainless steel and surface hardness evaluation by ultra micro hardness tester: Tanaka, T, Nakayama, H. and Kato, M. J. Soc. Mater. Sci. Jpn. (1995) 44 (497), 201–206 (in Japanese)

Impact assessment for laser hardened hypoeutectoid 2Cr13 martensite stainless steel was carried out on a specifically developed ball-on-flat impact tester. Results showed better impact behavior of 2Cr13 surfaces treated by a continuous wave CO2 laser than those under conventional heat treatment. Micro-hardness measurement demonstrated that the surface hardness of the laser treated specimens varied with the operation parameters of laser hardening. Scanning electron microscope (SEM) analysis and surface profile measurement suggested that the size of the impact wear scars of 2Cr13 specimens decreases with the increase of the surface hardness. EDX analysis showed that the oxidation resistance of the laser-hardened surfaces was relatively superior to their conventionally heat-treated counterparts. Compared with conventionally-treated 2Cr13 steel, the superior impact wear resistance of laser surface-processed steel was attributed both to grain refinement and to the higher martensite content near the surface that resulted from rapid cooling.