In-Situ Intrinsic Interface Strength Measurement at Elevated Temperatures and its Relationship to Interfacial Structure

A previously developed laser spallation technique has been modified to measure the tensile strength of thin film interfaces in-situ at temperatures up to 1100°C. Tensile strengths of Nb/A-plane sapphire, FeCrAl/A-plane sapphire and FeCrAlY/A-plane sapphire were measured up to 950°C. The measured strengths at high temperatures were substantially lower compared with their corresponding strengths at ambient temperature. For example, at 850°C, the interface tensile strength for the Nb/sapphire (151 ± 17 MPa), FeCrAl/sapphire (62 ± 8 MPa) and FeCrAlY/sapphire (82 ± 11 MPa) interface systems were lower by factors of approximately, 3, 5, and 8, respectively, over their corresponding ambient values. These results underscore the importance of using such in-situ measured values under operating conditions as the failure criterion in any life prediction or reliability models of such coated systems where local interface temperature excursions are expected. The results on alloy film interfaces also demonstrate that the presence of Y increases the strength of FeCrAl/Al₂O₃ interfaces.     

Formation of the structure and effective properties of composite material in the manufacture of shells with cross-ply reinforcement

Conclusion The proposed model of formation of the reinforcing framework in the manufacture of an axisymmetric shell by the CPW method makes it possible to numerically determine the thicknesses and rates of filling the layers, reinforcement angles as a function of the main parameters of the technological process, geometry of the mandrel, and characteristics of the reinforcing filament. It was established that the thicknesses of the layers, reinforcement rates and angles, and, as a consequence, the effective stiffness characteristics of the composite are substantially variable both along the meridian and over the thickness of the shell.Translated from Mekhanika Kompozitnykh Materialov, No. 5, pp. 609–617, September–October, 1992.The authors thank V. A. Frolov for the experimental results.     

Adaptive classification method and measurement of intermittent random process characteristics

Results are presented of an analytic construction and investigation of adaptive data classification algorithms for intermittent turbulence. A decision making rule is presented, relationships are derived to estimate the classification accuracy. A three-level procedure is described for processing the intermittency, including the calculation algorithms for the initial point, self-teaching, and optimal classification. It is shown that the method proposed permits realization of total automation of intermittency data processing.Translated from Teoreticheskaya i Prikladnaya Mekhanika, No. 18, pp. 119–123, 1987.     

Fragment methods for IR spectrum calculations of organophosphorus compounds

For highly toxic organophosphorus compounds on the limiting lists of the International Chemical Weapons Ban Treaty, fragment methods may be used for calculating their IR vibrational spectra; this is shown for O-alkyl alkylfluorophosphonates used as examples. The geometrical parameters and the parameters of the potential and electrooptic functions are found for the major fragments of these compounds. Due to this, fast predictive computation of IR spectra of O-alkyl alkylfluorophosphonates is possible, the accuracy of calculation being sufficient for spectral identification of these compounds; a database of the calculated IR spectra may be created.     

Laser fluorescence-absorption analysis of iodine-129 and nitrogen dioxide impurities in a special atmosphere

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 56, No. 1, pp. 116–121, January, 1992.     

Studies on Poly(Dialkoxyphosphazenes) for the Medical Applications

Abstract

The presence of trace of chlorine in poly(diorganophosphazenes) [-N=P(OR)2-]., where R = C₂H₅, CH₂CF₃, C₂F₅, C₄H₅, C₆H₁₃, C₈H₁₇, C₁₂H₂₅, CH₂C₆H₅ in many cases leads to the substantial changes of their physicochemical properties and limits application possibilities of this class of polymers especial for the medical materials. Despite the optimization of reaction conditions for each nucleophilic alkoxy substituent, the obtained poly(dia1koxyphosphaenes) exhibited some physicochemical anomalies.     

Synthesis of oligoorganosilsesquioxanes via acidohydrolytic polycondensation

Methyl acrylate oligosilsesquioxanes based on γ-methacryloxypropyltrimethoxysilane and its mixtures with phenyltrimethoxysilane have been synthesized through acidohydrolytic polycondensation and studied via NMR spectroscopy and MALDI-TOF mass spectrometry. It is shown that the addition of the aforementioned oligosilsesquioxanes to a dental composition based on 2,2-bis[p-(3-metacryloyloxy-2-hydroxypropoxy)phenyl]propane and triethylene glycol dimethacrylate improves the mechanical characteristics of cured polymer composites.     

Synthesis of oligomeric chlorophosphazenes in the presence of ZnCl2

With the use of ³¹P NMR spectroscopy and gas chromatography-mass spectrometry, the partial ammonolysis of PCl₅ by ammonium chloride in chlorobenzene in the presence of zinc chloride is investigated. The use of zinc chloride reduces the reaction time to 1.5 h and increases the yield of oligomeric chlorophosphazenes up to 95%. Some assumptions are made about the role of ZnCl₂ in the process and about the feasibility of the mechanism of formation of higher cyclic chlorophosphazenes, the hexamer and the octamer.