Improving the Physicochemical Properties of Fe–25Cr Ferritic Steel for SOFC Interconnects via Y-Implantation and Y2O3-Deposition

The present study investigated the role of the reactive-element effect (REE) in improving the corrosion resistance, chromium vaporization rate, and electrical conductivity of the Fe–25Cr ferritic steel modified either by means of yttrium implantation or chemical deposition of yttrium oxide from metaloorganic compound vapors. The corrosion kinetics of the Fe–25Cr steel, both pure and modified, were determined under isothermal conditions in air and an Ar–H₂–H₂O gas mixture at 1,073 K. A significant improvement in corrosion resistance was observed after surface modification. XRD and SEM–EDS investigations showed that the protective Cr₂O₃ layer formed the main part of the scale. Measurements of Cr vaporization rate in the air–H₂O gas mixture revealed that both surface modifications of the steel significantly suppressed the formation of volatile chromium compounds to a large degree. The yttrium-implanted steels oxidized both in air and the Ar–H₂–H₂O mixture were characterized by the lowest area specific resistance and thereby did not exceed the acceptable ASR level (0.1 Ω cm²) for interconnect materials in the temperature range of 973–1,073 K, unlike pure steel and the steel coated with Y₂O₃.     

Industrial applications of the agglomeration process

Environmental, technological and economic problems caused by utilization of low quality and low rank coals and serious concerns related to a growing number of polluted industrial waste sites have significantly increased interest in further development and application of oil agglomeration technology. Study performed at the Alberta Research Council on the various applications of the spherical agglomeration process led to the development of different technologies applicable for coal cleaning, upgrading, handleability improvement or moisture reduction. The other important applications were recovery of combustible material from rejects and settling ponds and remediation of soils contaminated with various hydrocarbons.

The preparation and handling of fine coal is a key issue to many coal mine operators and the efficient recovery of coal from fines streams could have a profound effect on increased plant productivity and reduction of the potential environmental liabilities associated with waste generation, accumulation and disposal.

To overcome the problems associated with coal fines and hydrocarbon-contaminated soils, ARC researchers have, over the last 20 years, placed particular emphasis on the development and testing of improved coal preparation and soil remediation technologies.     

Study washboarding phenomenon in frame sawing machines

The paper concerns washboarding phenomenon where for every kind of sawing a very regular pattern is characterised by a sinusoidal – like variation in board thickness. That pattern is an effect of the saw blade lateral vibrations. It is palpable that these vibrations are detrimental to the cutting process, and lead to poor surface quality and dimensional accuracy, and raw material waste. For band saws in the contemporary literature models explaining a washboarding phenomenon are supported on self-excited (self-induced) vibration theories. However, these explanations cannot be simply broadened into the washboarding phenomenon in frame sawing machines. In this work based on theoretical and experimental investigation the washboard pattern formation is clarified by the authors with the use of a theoretical model, in which the rugged surface is an effect of vibrations generated by lateral cyclic loading and lagged wave formation. The authors hope that their obtained results contribute significantly to further understanding of this important but complicated phenomenon.     

ICP-MS multi-element profiles and HPLC determination of furanic compounds in commercial tequila

In this work, inductively coupled plasma mass spectrometry determination of Ag, As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Sb, Se, Tl, V, Zn, Th and U in commercial tequila has been accomplished. The samples were tenfold diluted (1% HNO₃), ethanol (4% v/v) was added to multi-element calibration solutions and possible spectral interferences were controlled by the use of collision/reaction cell technology. The results obtained in the analysis of 40 brands showed low concentration levels of the elements, in agreement with actual Mexican regulations, except for copper. Statistically significant differences were found between the concentration levels of copper, molybdenum, mercury and thorium in 100% agave and mixed tequila brands. In search of parameters useful for discrimination between 100% and mixed tequila categories, 5-hydroxy-methylfuraldehyde, 2-furoic acid (2-FAC), 2-furaldehyde (2-FAL), 2-furylmethylketone (2-FMC), 5-methylfuraldehyde (5-MFA), syringaldehyde (SIR) were also determined, using simple and fast reversed phase chromatographic procedure. Principal component analysis was used as the variable reduction procedure. In the multivariate model obtained, a natural separation of 100%, mixed and aged tequilas has been observed in the space defined by the first three principal components that accounted for 94% of total system variability. The analysis of correlation revealed statistically significant direct relationship between 100% tequila and 2-FAL, 5-MFA, Cu (β = 0.781, p = 0.028; β = 0.688, p = 0.042; β = 0.664, p = 0.046, respectively), between mixed tequila and Hg, Th, Mo (β = 0.948, p = 0.000; β = 0.905, p = 0.002; β = 0.867, p = 0.012, respectively) and between aged tequila and SIR, 2-FAC (β = 0.937, p = 0.000; β = 0.889, p = 0.000, respectively). In conclusion, among 25 parameters initially selected, the above 8 (2-FAL, 5-MFA, Cu, Hg, Th, Mo, SIR, 2-FAC) could be useful in the multivariate discrimination between tequila categories.     

Lattice and Grain‐Boundary Diffusion of Al in Tetragonal Yttria‐Stabilized Zirconia Polycrystalline Ceramics (3Y‐TZP) Analyzed Using SIMS

Aluminum oxide was deposited on the surface of 3 mol% yttria‐stabilized tetragonal zirconia polycrystals (3Y‐TZP). The samples were annealed at temperatures from 1523 to 1773 K. Diffusion profiles of Al in the form of mean concentration vs. depth in B‐type kinetic region were investigated by secondary ion mass spectroscopy. The experimental results for the lattice diffusion (D_B) and grain boundary diffusion (D_GB) are as follows: and where δ is the grain‐boundary width and s is the segregation factor.     

Optimization of impedance measurements using ‘chirp’ type perturbation signal

The paper presents a novel method of impedance measurements using the non-stationary ‘chirp’ signal. Variable sampling frequency has been employed in a process of acquisition of the voltage perturbation and current response signals. Such solution allows significant decrease in a number of data necessary to obtain an impedance spectrum as well as simplification and acceleration of the calculation process. It has been found that an accuracy of the results obtained with this method was directly proportional to the frequency resolution, with which impedance values were obtained.     

Evaluation of corrosion inhibition of brass-118 in artificial seawater by benzotriazole using Dynamic EIS

The paper presents the results of corrosion behaviour of brass-118 in artificial seawater and the inhibitor effect of benzotriazole (BTA) by using a novel method called dynamic electrochemical impedance spectroscopy (DEIS). This method allows the tracing of the dynamics of the corrosion and the inhibition process based on the evaluation of electrical parameters of the equivalent circuit. Instantaneous impedance spectra recorded up to 10 h show that an exposure of few hours is not enough for the determination of inhibition efficiency. The results indicate the usefulness of DEIS technique in the field of inhibitor research.     

Quadratic Cohen representations in spectral analysis of serration process in Al–Mg alloys

Important from mechanical point of view the Portevin–Le Chatelier serration phenomenon is being characterized by a complicated spectral profile. As a typical example of nonstationary processes it demands a special treatment allowing to follow the evolution of energy of stress fluctuations as a function of strain. The authors suggest the utilization of a compact system of quadratic transformations, known as Cohen class, as a technique enabling the reliable analysis of serration processes. In this elaboration a comparison of the application of various Cohen decompositions to analyze frequency bands has been introduced.     

Drainage and economic utilization of methane from coal seams in the Jastrzebie mining-field

The paper presents the resources and present status of coal-seam methane from the mining field of JSW S.A., as well as trends in its application both in JSW S.A. plants and elsewhere. For the period 1999–2001, the dynamics of growth of methane utilization are shown. Perspectives of methane drainage are considered, with regard to both work and the realization of restructuring programs in the mining industry. Demand and supply of methane are discussed, taking into account real and potential opportunities. An assessment was made of the emissions to the atmosphere both of methane and of other pollutants. An evaluation of the influence exerted by these measures on the performance of cogeneration of heat and electricity has been prepared. Several projects in progress are described, namely the increase of gas-firing in existing boiler installations, investment projects referring to the installation of gas engines for cogeneration of heat and electricity, utilization of the distribution network for the maximum utilization of gas and the designs of power-generation systems (using methane) for air conditioning in the mines.