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We have systematically investigated the elastic properties (ρ, VP, VS, K, μ and σ) of eight SiO2–TiO2 glasses, varying in composition from 1.3 to 14.7 wt% TiO2, as a function of pressure up to 0.5 GPa by the pulse superposition (PSP) ultrasonic technique, and two compositions (1.3 and 9.4 wt% TiO2) up to ~5.7 GPa by Brillouin scattering in a diamond anvil cell. The parameters were also measured after annealing to 1020 °C. Composition–elasticity relationships, except for K and σ, are more or less linear; the annealing simply makes the relationships more uniform (less scatter). There is excellent agreement between the ultrasonic and Brillouin measurements at ambient and high pressure. The pressure-induced anomalous elastic behavior (negative dVP/dP and dK/dP) becomes more negative (more compressible) with the increasing TiO2 content. Correspondingly, the acoustic Grüneisen parameters become more negative with increases in the TiO2 content, reaching a minimum near ~8–10 wt% TiO2. The comparison of the low- and high-pressure ultrasonic and Brillouin VP and VS in two glasses (1.3 and 9.4 wt% TiO2) shows excellent agreement, defining the reversible elastic behavior at low pressures and irreversible behavior at higher pressures (≥5.7 GPa) well. This result is consistent with our previous high-pressure Raman study showing an irreversible structural change in a similar pressure range.

The single‐crystal elastic constants Cij of β‐cubic PbF2 (fluorite type) have been measured to ∼0.3 GPa at ambient temperature and to 573 K at ambient pressure. The measured Cij are (in gigapascals (GPa)): C11 = 96.075 ± 0.094, CS = (C11 – C12)/2 = 24.475 ± 0.018, and C44 = 20.835 ± 0.012. The results from the least squares linear fit of the pressure data to ∼0.3 GPa yield dC11/dP = 7.79 ± 0.08, dCs/dP = 0.21 ± 0.08, and dC44/dP = 0.82 ± 0.02, and the temperature data in the range of 298–373 K give (in GPa per degree × 102): dC11/dT = −5.63 ± 0.05, dCS/dP = −1.26 ± 0.03, and dC44/dT = −1.11 ± 0.07. The pressure derivatives do not give any indication of the monotropic transition at ≤0.4 GPa; likewise, the temperature derivatives do not indicate the onset of superionicity at high temperatures. Relative stability of the α, β, and β′ phases of PbF2 is discussed in light of thermodynamic parameters.

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In the 1960s, Opitz discovered the formation of complex oxide protective layers (Belag) on worn surfaces of tools when cutting Ca deoxidized steel. Belag formation is used in a free-cutting technique for steel and cast iron because it significantly reduces diffusional wear by preventing direct contact between the tool and work material; hence, tool life can be dramatically prolonged. For Belag to form, one condition is that the tool material should contain TiC. It has been reported that Belag adheres to tool surfaces because TiC in the tool oxidizes and reacts with Belag. Our study aims to clarify the formation and adhesion mechanisms of Belag. In this study, Ca deoxidized steel was machined with noncoated carbide P10 tools, and the state of the interface between the tool and Belag layer was investigated by transmission electron microscopy (TEM) and elemental analyses. As a result, we found that Belag directly adhered to Ti carbide (Ti–W–C) particles on tool surfaces. In contrast, Belag did not directly adhere to WC or Co on tool surfaces. Unlike previous studies, we could not confirm the formation of the TiC oxide or its oxide layer near the interface to which Belag adhered. In addition, when we machined a Ca deoxidized steel containing MnS, a CaS layer formed in Belag at the interface between the tool and Belag layer.

Various telecommunication techniques using supersonic, electromagnetic or light waves have been developed for application to remotely controlled machine operation systems, especially for microsystems. A light wave communication technique using fluorescent light in an optical fiber was considered to be applicable for this purpose. The fundamental communication properties of fluorescent-doped plastic fiber have been examined to realize such a system in a specific narrow space. As a result, the detectable distance of 5m with resolution of 5.6 mm and a communication rate of approximately 500 kbps was obtained.