Investigation of Wear and Corrosion Behaviour of AISI 316 L Stainless Steel Coated By ESD Surface Modification

Protection of Metals and Physical Chemistry of Surfaces - AISI 316 L austenitic stainless steel is widely used in various sectors of the industry (chemical, petro-chemical industry, paper industry,...     

The Journey of Phenolics from the First Spark to Advanced Materials

The emergence, historical and recent developments of phenolic resins are reviewed. The history of the invention of the first man made plastics and a short bibliography of the inventor Leo H. Baekeland is provided. Moreover, the basic chemistry of phenol-formaldehyde resins, as synthesis of resol and novolak, their structures, variations, and curing are discussed. Modification of these resins and molecular designs for specific applications in retro perspective are highlighted. This review also provides a comprehensive account on the development of benzoxazine resins as an alternative to classical phenolics. In addition to the benzoxazine synthesis and their curing mechanism, special monomers and polybenzoxazine precursors as curable thermoplastics are reviewed. Besides classical chemicals, the potential of renewables for phenolic resin production is also highlighted. Finally, the relative advantages and disadvantages of these systems are discussed and their future potentials are presented.     

Modeling the ultrasonic cavitation‐enhanced removal of nitrogen oxide in a bubble column reactor

A model study of the sonochemical removal of nitric oxide (NO) in a bubble column reactor is presented. The detailed model is developed to investigate the actual cavitation phenomena taking place during the absorption of NO. The expansion and subsequent collapse of cavitation bubble according to the theory of cavity collapse—initially developed by Lord Rayleigh and then improved on by coupling the energy balance equation of the bubble and the chemical reactions taking place inside the cavity to calculate the composition of different species formed during the collapse—are modeled. The model takes into consideration (1) cavitation bubble dynamics, (2) generation and transfer of oxidizing species from bubble collapse through reaction kinetics, (3) transfer of NO from gas to liquid, and (4) chemical reactions of oxidizing species with dissolved NO. The results of the simulations surprisingly indicate that the chemistry induced by ultrasonic cavitation cannot explain the absorption of NO beyond about 30% of the inlet concentration if the mass transfer is assumed to be the same as that in the bubble column without ultrasound. When experimental values of mass‐transfer coefficients, calculated in the studies by other researchers (which are in the range of about five times the physical mass‐transfer coefficient in a bubble column), are used, absorption up to 80% are calculated in the simulations consistent with experimental results obtained from the sonochemical bubble column reactor. The present model provides a framework on which more robust and rigorous models can be developed for the complex gas‐liquid sonochemical systems and reactors. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2397–2411, 2012     

Quinoxaline derivatives as long wavelength photosensitizers in photoinitiated cationic polymerization of diaryliodonium salts

The present paper is focused on visible light initiated cationic polymerizations. Photoinitiated polymerization of representative vinyl ether and oxirane monomers using two quinoxaline derivatives; namely (2-(2,3-dihydrobenzo [b][1,4]dioxin-6-yl)-3-(2,3-dihydrobenzo[b]-[1,4]dioxin-7-yl)-5-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-8-(2,3-dihydrothieno[3,4-b][1,4]dioxin-7yl) quinoxaline) (DBQEd) and 2,3,5,8-tetra(thiophen-2-yl)quinoxaline (TTQ) are studied. Novel dyes based on the quinoxaline skeleton are employed as efficient photosensitizers in cationic photopolymerizations. Polymerizations were initiated at room temperature upon irradiation with long-wavelength UV and visible lights in the presence of diphenyliodonium hexafluorophosphate (Ph₂I⁺PF₆^?). The progress of the polymerizations was monitored by optical pyrometry (OP). Solar irradiation is also employed to carry out the cationic polymerization of a diepoxide monomer in the presence of air.     

Estimated anthropometric measurements of Turkish adults and effects of age and geographical regions

The purpose of this paper is to estimate the anthropometric characteristics of the Turkish population by geographical region, age and gender. A survey of 4205 samples consisting of 2263 male and 1942 female civilian subjects was done in the year of 2007. It contains data from all seven geographical regions of Turkey and from all age groups. In the study, height and weight of the subjects were measured by age. Then, these data were used for estimating anthropometric measurements of the Turkish population. The main result of this study is the anthropometric measurements table for Turkey which shows 37 measurements that are commonly used in industry. The anthropometric measurements that are used to make the designs fit human shape and the human/machine or human/environment interface should be updated through time due to changing body types over time (secular trends) due to numerous factors. In this study, we not only update these variables, which are 30 years old, but also investigate the age and region effects on stature and weight of Turkish population.Relevance to industry: During the design phase of a product, incorporating anthropometric information would yield more efficient designs, which are more user friendly, safer and enable higher performance and productivity. So the anthropometric measurements table that is extracted from this study can be used by industry to produce better human oriented products for Turkish population.     

Assessment of odorous VOCs released from a main MSW landfill site in Istanbul-Turkey via a modelling approach

An air pollution modeling study was conducted to investigate the odorous effects of volatile organic compounds (VOCs) emissions from a sanitary landfill area on ambient air quality. The atmospheric dispersion of hydrogen sulfide (H₂S) and 22 VOCs was modeled. Industrial Source Complex v3 Short Term (ISCST3) model was used to estimate hourly concentrations of odorous VOCs over the nearest residential area. Odor thresholds of VOCs of interest were also found in the literature. Results showed that short-term averages of three odorous VOCs, namely ethyl mercaptan, methyl mercaptan and hydrogen sulfide, exceeded their odor thresholds, which are reported to be 0.022, 0.138 and 11.1 μg/m³, respectively, at several points within the domain. Their highest concentrations within Gokturk County were estimated to be 0.09387 μg/m³ for ethyl mercaptan, 0.07934 μg/m³ for methyl mercaptan and 6.315 μg/m³ for hydrogen sulfide. Short-term model results revealed the occasional odor problems being reported for Gokturk County. Hourly concentrations were used to obtain frequencies of odor episodes in Gokturk County via a probability analysis. The results showed that ethyl mercaptan concentrations did not exceed its odor threshold during more than 8.84% of the time. Similarly, the maximum odor episode frequencies for methyl mercaptan and hydrogen sulfide were 0.98% and 0.34% of the time, respectively.     

Tribological Characteristics of Calophyllum inophyllum–Based TMP (Trimethylolpropane) Ester as Energy-Saving and Biodegradable Lubricant

The purpose of this research is an experimental study of Calophyllum inophyllum (CI)-based trymethylolpropane (TMP) ester as an energy-saving and biodegradable lubricant and compare it with commercial lubricant and paraffin mineral oil using a four-ball tribometer. CI-based TMP ester is a renewable lubricant that is nonedible, biodegradable, and nontoxic and has net zero greenhouse gases. The TMP ester was produced from CI oil, which has high lubricity properties such as higher density, higher viscosity at both 40°C and 100°C and higher viscosity index (VI). Experiments were conducted during 3,600 s with constant load of 40 kg and constant sliding speed of 1,200 rpm at temperatures of 50, 60, 70, 80, 90, and 100°C for all three types of lubricant. The results show that CI TMP ester had the lowest coefficient of friction (COF) as well as lower consumption of energy at all test temperatures, but the worn surface roughness average (R_a) and wear scar diameter were higher compared to paraffin mineral oil and commercial lubricant. Before 80°C, CI TMP ester actually has a higher flash temperature parameter (FTP) than paraffin mineral oil and as the temperature increases, the FTP of TMP ester decreases. The worn surfaces of the stationary balls were analyzed by scanning electron microscopy (SEM) and results show that CI TMP ester has the highest wear compared to paraffin mineral oil and lowest wear compared to commercial lubricant. However, CI TMP ester is environmentally desired, competitive to commercial lubricant, and its use should be encouraged.     

Thermal insulation enhancement in concretes by adding waste PET and rubber pieces

The relative change in insulation property of the ordinary concrete due to adding polymeric based waste material is experimentally investigated here. The polyethylene (PET) bottle and automobile tire pieces, which can easily be obtained from the environment with almost no cost, are shredded and added into ordinary concrete to examine heat insulation behaviors of specimens. Five different concrete samples (one ordinary concrete, one concrete with scrap rubber pieces and three concretes with waste PET bottle pieces of various geometries) are considered. The adiabatic hot-box technique is used for comparing effective thermal transmittances of these concrete samples. The results reveal that proper addition of selected waste materials into concrete can significantly reduce heat loss or improve thermal insulation performance. The degree of improvement in thermal insulation is found to vary with the added waste material and geometry of shredded-pieces.