Experimental Study on Tensile Characteristics of Layered Carbonaceous Slate Subject to Water–Rock Interaction and Weathering

The transverse isotropy of rock masses formed by sedimentation is a common stratum environment in engineering, and the physical–mechanical properties can degrade due to water–rock interaction (WRI) and natural weathering, which potentially lead to the instability or collapse of tunneling, slopes and mining. Taking the carbonaceous slate of the Muzhailing tunnel as the research object, two types of specimens, which include oven-drying (instant drying in oven after fabrication) and natural air-drying (static weathering for 60 days after fabrication) were prepared, respectively, after which Brazilian tests were carried out and the tensile properties were analyzed under the two conditions. The experimental results showed that the two kinds of carbonaceous slate all show brittle failure, but the mechanical response such as failure displacement and peak load is obviously different. The tensile strength of the specimens is significantly all affected by the bedding, while the cleavage failure patterns of the two kinds are affected to different degrees. The softening coefficient of the natural air-drying specimen is 0.11–0.13, which implies that WRI and natural weathering play a vital role in the course of rock failure but have little influence on the transverse isotropy tensile property of bedding. Moreover, the mechanisms of specimen failure subject to WRI and 60 days’ weathering were explained by the SEM technique, which analyzed the micro-components and observes the process of specimen deterioration due to physicochemical reaction, the gradual development of cracks and erosion by weathering

Nanocoatings in medicine: antiquity and modern times

Whilst nanotechnology particularly focuses upon the power of working at the nanoscale, often with reference to particles or atoms, nano-based materials or nanocoatings upon ordinary classed materials, are equally as potent. Nanocoatings are prevalent across a multitude of disciplines ranging from engineering through to medicine. A wide range of materials and techniques has been employed to produce nanocoatings for a given purpose. This chapter explores a number of aspects of nanocoatings and provides a brief overview of the origins and development of coating as a concept. It also delves into the concept of nanocoating, examining exactly what is a nanocoating and what production methods are employed in present day. Predominantly, attention is focused upon the existence of nanocoatings used to improve mechanical properties, offer novel functionality such as extreme water repellence (superhydrophobicity) or their implementation in the pharmaceutical, medical and dental industries (e.g. the coating of dental and medical implants). The feasibility and advantages of working at the nanoscale to engineer coatings are discussed, critically assessing whether added benefits are actually achieved. © 2015 Elsevier Inc. All rights reserved