A study has been made of Hertzian contact damage in compressive shear stress field beneath the contact area. The observed microcrack density increases with grain size, porous and dense liquid-phase-sintered aluminas. Indentation stress–strain curves show increasing nonlinearity as the implying a threshold microstructural scale for crack initiation. In contrast, the micromechanisms controlling f...

Loop heat pipes (LHPs) are used in many branches of industry, mainly for cooling of electrical elements and systems. The loop heat pipe is a vapour-liquid phase-change device that transfers heat from evaporator to condenser. One of the most important parts of the LHP is the porous wick structure. The wick structure provides capillary force to circulate the working fluid. To achieve good thermal...

As a reaction to the increasing noise pollution, caused by the expansion of airports close to residential areas, porous trailing edges are investigated to reduce the aeroacoustic noise produced by flow around the airframe. Besides mechanical and acoustical investigations of porous materials, the fouling behavior of promising materials is an important aspect to estimate the performance in long-t...

Sintered porous structures are ubiquitous as heat transport media for thermal management and other applications. In particular, low-porosity sintered packed beds are used as capillary-wicking and evaporation-enhancement structures in heat pipes. Accurate prediction and analysis of their transport characteristics for different microstructure geometries is important for improved design. Owing to ...

A process is described which involves infiltration of aluminum nitrate into partially sintered (porous) zircon bodies. Infiltration kinetics were studied using infiltration curves with two distinct regions. The final infiltrated samples were sintered at 1600 °C for 2 h and yielded specimens containing the tetragonal zirconia.The experimental results show that in spite of the similar porosity of...

Liquid-vapor, phase-change heat transfer using wicks can provide reliable and high flux cooling capability, especially in microgravity applications. However, the maximum removal capacity, also known as Critical Heat Flux (CHF), is related to capillary-driven liquid supply limit and/or vapor limit. A key develop a novel wick structure, offering efficient well pathways. In this study, Bare Surfac...

: Because of its optical and electrical properties, large surfaces, and compatibility with standard silicon processes, porous silicon is a very interesting material in photovoltaic and microelectromechanical systems technology. In some applications, porous silicon is annealed at high temperature and, consequently, the cylindrical pores that are generated by anodization or stain etching reorgani...

A numerical model of the evaporating liquid meniscus under saturated vapor conditions in wick microstructures has been developed. Four different wick geometries representing the common wicks used in heat pipes, viz., wire mesh, rectangular grooves, sintered wicks and vertical microwires, are modeled and compared for evaporative performance. The solid-liquid combination considered is copper-wate...

This study investigates phase transformation and mechanical properties of porous NiTi alloys using two different powder compacts (i.e., Ni/Ti and Ni/TiH2) by a conventional press-and-sinter means. The compacted powder mixtures were sintered in vacuum at a final temperature of 1373 K. The phase evolution was performed by in situ neutron diffraction upon sintering and cooling. The predominant pha...

Ionic electrospray thrusters are promising candidates for CubeSat propulsion systems in space, due to their low power requirement and small form factor. Current technology has demonstrated thrust levels of 10 40pN, enabling station keeping and attitude adjustment maneuvers. Densification of emitter arrays could increase the thrust density and potentially expand the application space for electro...