Kerbempfindlichkeit und kritische Spannungsintensitätsfaktoren von Hartmetallegierungen

Elektronenmikroskopische Untersuchung der Bruchflächen sowie Ermittlung der Kerbempfindlichkeit von Wolframcarbid-Kobalt- und Wolframcarbid-Titancarbid-Tantalcarbid-Kobalt-Hartmetallegierungen. Verfahren zur Messung der kritischen Spannungsintensitätsfaktoren bei Hartmetallen. In Biegeversuchen an gekerbten Proben Ermittlung von K_Ib-Werten; Untersuchung ihrer Legierungs- und Temperaturabhängigkeit sowie der Möglichkeiten der Kerbausheilung. Arbeitshypothese zur Deutung von Zusammenhängen zwischen den K_Ib-Werten und dem Verschleißverhalten von Hartmetallegierungen.     

Herstellung von Stäben und Rohren aus Metallpulvern durch Strangpressen

Herstellung von Halbzeug (Stäbe, Rohre) durch Heißstrangpressen von bei Raumtemperatur gepreßten porigen Blöcken aus durch Wasserverdüsung hergestelltem Chrom-Nickel-Stahlpulver mit rd. 0,6% G, 18,0% Cr und 11,0% Ni und Chrom-Aluminium-Stahlpulver mit rd. 0,03% C, 0,5, 1,0 oder 1,5% Si, 5,0% Al, 2,0% Co und 26,0% Cr sowie naßchemisch gewonnenem Nickelpulver mit 99,56% Ni. Untersuchung der physikalischen und mechanischen Eigenschaften der Stäbe und Vergleich der gefundenen Werte mit denen der schmelzmetallurgisch hergestellten Werkstoffe gleicher chemischer Zusammensetzung.     

Equilibria of H2S and CO2 in triethanolamine solutions

The equilibrium solubility of H₂S and CO₂ has been measured in 2.0, 3.5 and 5.0 mol/L triethanolamine solutions. Data were obtained at temperatures of 25°, 50°, 75°, 100° and 125°C at partial pressures of the acid gases ranging from 0.01 to 6360 kPa. Enthalpies of solution were calculated from the solubility data.     

Irreversible photobleaching,photorefraction and photoexpansion in GeS2 amorphous film

The photoinduced irreversible effects in thermally evaporated amorphous GeS₂ films were investigated. The magnitude of the photobleaching induced by gap photons was found at around ≈13%. The photoinduced increase in the optical band gap and the increase in the slope of the short wavelength absorption edge are discussed within the Davis–Mott model and within Tauc's model for optical transitions in amorphous solids. Based on the optical measurements and the Atomic Force Microscopy we also observed photoexpansion at around ≈4.8% accompanied by a decrease in the refractive index from n = 2.02 for the virgin film to n = 1.94 for a film illuminated until a nearly steady state.     

Strain and temperature effects in indium-tin-oxide sensors

Indium-tin-oxide (ITO) thin films strain gages were prepared by reactive sputtering onto both high purity alumina and lanthanum stabilized zirconia substrates. We report the piezoresistive response of these ITO gages in the temperature range 350-1500 °C up to 1000 microstrain (με). Strain response and gage factors are reported for ITO in both tension and compression. The data suggest that not only is there an annealing component but also a strain component of the piezoresistive change with time at temperature. The effects in both tension and compression are reported.     

Temperature-sensitive europium(III) probes and their use for simultaneous luminescent sensing of temperature and oxygen

Highly photostable and strongly luminescent europium(III) beta-diketonate complexes are presented that can act as new probes for optical sensing of temperature. They can be excited with the light of a 405-nm LED and possess strong brightnesses. The decay times of the probes contained in a poly(vinyl methyl ketone) film and in poly(tert-butyl styrene) microparticles are highly temperature-dependent between 0 and 70 degrees C. The temperature-sensitive microparticles were dispersed, along with oxygen-sensitive microbeads consisting of a palladium porphyrin oxygen indicator in poly(styrene-co-acrylonitrile), in a thin layer of a hydrogel to give a dually sensing material which is excitable by a single light source. The two emissions can be separated by appropriate optical filters. The response to oxygen and temperature is described by 3D plots, and unbiased values can be obtained for temperature and oxygen, respectively, from the two luminescence signals if refined in an iteration step. The sensing scheme is intended for use in temperature-compensated sensing of oxygen, in contactless sensing of oxygen and temperature in (micro)biological and medical applications, in high-resolution oxygen profiling, and for simultaneous imaging of air pressure and temperature in wind tunnels.     

Modified dual lifetime referencing method for simultaneous optical determination and sensing of two analytes

Simultaneous fluorometric sensing of two analytes becomes possible using a modified dual lifetime referencing (m-DLR) method. In this scheme, two luminescent indicators are needed that have overlapping absorption and emission spectra but largely different decay times. They are excited by a single light source, and both emissions are measured simultaneously. In the frequency domain m-DLR method, the phase of the short-lived fluorescence of a first indicator is referenced against that of the long-lived luminescence of the second indicator. The analytical information is obtained by measurement of the phase shifts at two modulation frequencies. The method is demonstrated to work for the case of dually sensing oxygen and carbon dioxide. It benefits from simple instrumentation and optical setup. The approach is perceived to be of wide applicability. Examples include (1) analysis of two luminescent analytes, (2) analytical determinations that make use of two probes, and (3) sensing of two species such as carbon dioxide and oxygen (as demonstrated here), or oxygen and chlorophyll, provided the luminophores meet the condition of having largely different decay times and overlapping absorption and emission spectra.