Atomically thin molybdenum disulfide (MoS2) offers potential for advanced devices and an alternative to graphene due to its unique electronic and optical properties. The temperature-dependent Raman spectra of exfoliated, monolayer MoS2 in the range of 100–320 K are reported and analyzed. The linear temperature coefficients of the in-plane E 2g 1 and the out-of-plane A 1g modes for both suspended and substrate-supported monolayer MoS2 are measured. These data, when combined with the first-order coefficients from laser power-dependent studies, enable the thermal conductivity to be extracted. The resulting thermal conductivity κ = (34.5 ± 4) W/mK at room temperature agrees well with the first-principles lattice dynamics simulations. However, this value is significantly lower than that of graphene. The results from this work provide important input for the design of MoS2-based devices where thermal management is critical.

The Dusty Plasma Experiment (DPX) is a new experimental plasma device at Fisk University. DPX is constructed from two, 4 in. diam ISO 100 stainless steel six-way crosses. Initial experiments have successfully produced argon dc glow discharge plasmas. Measurements of the plasma parameters using Langmuir probes, in the absence of the dust particles, give plasma densities n∼1015 m−3 and electron temperatures ranging from Te=2 to 5 eV. Dusty plasmas are made by suspending 40 μm diam silica (SiO2) particles in the argon plasma. Dust clouds in the DPX device have densities nd∼109–1010 m−3. This paper describes the hardware and initial operation of the DPX device. Measurements of the three dimensional spatial structure of dust clouds are discussed. Dust acoustic modes with frequencies in the range f=10–20 Hz in the dust clouds are also identified. Particle image velocimetry techniques are used to characterize the spatial distribution and the temporal evolution of the velocities of the dust particles in the plasma.

Abradable linings are frequently used on the inside of aero-engine casings. During the operation of engine, the rotating blades may strike the lining of the casing. The wear mechanisms present during these incursions have been re-produced on a scaled test rig platform. Previously, characterisation of the wear has been performed using a stroboscopic imaging technique in order to identify the different wear mechanisms at the incursion conditions investigated. In the present study a dynamometer has been included in the test arrangement allowing the measurement of the contact force. This approach has then been combined with sectioning of the abradable test samples, in order to investigate the material response to the different incursion conditions. The wear results, the cutting force and material structure post-incursion show a high degree of correlation. At low incursion rates, significant consolidation and solidification of abradable material was observed, whilst at the same time adhesive transfer to the blade was recorded along with a low tangential to normal force ratio.At high incursion rates, little solidification and consolidation was observed, together with negligible adhesion and a higher tangential force, suggesting a cutting mechanism.Transitions in material behaviour, wear mechanism, and force ratio were observed at the same incursion condition, further highlighting the link between the different experimental measurements.

Graphite nanoplatelets (GNP) were prepared by a high-pressure homogenisation process (HPHP) via exfoliation of bulk graphite, yielding GNP in the form of square shaped platelets with lateral dimensions on the micrometre (μm) scale and thicknesses on the nanometre (nm) scale (<200 nm).

In aero-engines it is possible for the blades of the compressor, turbine or fan to incur into their casings. At these interfaces a lining of composite abradable material is used to limit damage to components and thereby sustain the efficiency and longevity of the engine as a whole. These composite materials must have good abradability and erosion resistance. Previously, the wear mechanisms at the contact between the blade and the coating have been characterized using stroboscopic imaging and force measurement on a scaled test-rig platform.This work is focused on the characterization of the wear mechanism for two different of abradable lining. The established stroboscopic imaging technique and contact force measurements are combined with sectioning of the abradable material in order to analyse the material`s response during the tests. A measure of the thermal properties and the resulting temperature of the linings during the test have also been made to further understand the effect of coating hardness.The wear mechanism, material response, contact force and thermal properties of the coating have been used to characterize the different material behaviour with different hardness. At low incursion rates, with a soft coating, the blade tip becomes worn after an initial adhesive transfer from the coating. Post-test sectioning showed blade material and significant compaction present in the coating. The harder coating produced adhesion on the blade tip with solidification observed in the coating. Thermal diffusivity measurements and modelling indicated that thermally driven wear observed was as a consequence of the increased number of boundaries between the metal and hBN phases present interrupting heat flow, leading to a concentration of surface heat. At higher incursion rates the wear mechanism is more similar between the coatings and a cutting mechanism dominates producing negligible adhesion and blade wear.