Nano-Tech OHTL Insulators

This chapter detects types and structure of ceramic and polymeric insulators. It also sheds light on improving efficiency and high voltage distribution through insulators string toward utilizing nanotechnology techniques. Furthermore, this chapter takes interest in displaying the effects of nanoparticles on overhead transmission lines (OHTL) insulators and high voltage distribution on suspension insulators. The importance and features of using polymeric and non-ceramic suspension insulators have been recently detailed. Thus, this chapter tackles and designs recent models for using individual and multiple nanoparticles in polymeric OHTL suspension insulators. It draws forecasts and recommendations for developing suspension insulators by using nanotechnology techniques.

Biphasic osteochondral scaffold fabrication using multi-material mask projection stereolithography

Purpose This study aims to develop a multi-material stereolithography (MMSL) technique to directly fabricate a biphasic osteochondral scaffold. Design/methodology/approach A bespoke prototype MMSL system was developed based on a bottom-up mask projection approach. The system was controlled by a multi-material fabrication algorithm with minimum number of switching cycles during fabrication. A variable-power light source was used to fabricate materials with significantly different curing characteristics. The light-curable poly(ethylene glycol) diacrylate (PEGDA) hydrogel and beta-tricalcium phosphate (β-TCP) ceramic suspension were used for fabricating the biphasic osteochondral scaffold. Findings The bonding strength of the multi-material interface is shown to be mainly affected by the type of photopolymer, rather than the switching of the materials in MMSL. Lighting power densities of 2.64 and 14.98 mW/cm2 were used for curing the PEGDA hydrogel and the ß-TCP ceramic suspension, respectively. A biphasic osteochondral scaffold with complex interface was successfully fabricated. Originality/value This study proposes a potential technical method (MMSL) for manufacturing a complex biphasic osteochondral scaffold composing a PEGDA hydrogel/ß-TCP ceramic composite in a time-efficient and precise manner. The designed bone-cartilage scaffold interface and the surface of the cartilage scaffold can be precisely manufactured.

Ceramic Additive Manufacturing Using VAT Photopolymerization

The popularity of additive manufacturing for producing porous bio-ceramics using vat photopolymerization in the recent years has gained a lot of impetus due to its high resolution and low surface roughness. In this study, a commercial vat polymerization printer (Nobel Superfine, XYZprinting) was used to create green bodies using a ceramic suspension consisting of 10 vol.% of alumina particles in a photopolymerizable resin. Four different sizes of cubical green bodies were printed out. They were subjected to thermal processing which included de-binding to get rid of the polymer and thereafter sintering for joining of the ceramic particles. The porosity percentage of the four different sizes were measured and compared. The lowest porosity was observed in the smallest cubes (5 mm). It was found to be 43.3%. There was an increase in the porosity of the sintered parts for the larger cubes (10, 15 and 20 mm). However, the difference in the porosity among these sizes was not significant and ranged from 61.5% to 65.2%. The compressive testing of the samples showed that the strength of the 5-mm cube was the maximum among all samples and the compressive strength decreased as the size of the samples increased. These ceramic materials of various densities are of great interest for biomedical applications.

Slip Casting Used as a Forming Technique for Hydroxyapatite Processing

Ceramic materials have particular properties when compared to other classes of materials, exhibiting poor ductility as an example. Slip casting is a widely used ceramic forming technique, and already established in the literature and in the ceramic industry. This study aims to present slip casting as a processing route for producing hydroxyapatite (HA) struts, and show the thermal phase stability. The ceramic suspension was produced and stabilized with hydroxyapatite powder, deionized water and polyethylene glycol 400. The slip was poured into gypsum mold. The green bodies were heat treated at 900 and 1100°C. Hydroxyapatite was the only phase present in all samples, before and after heat treatments. Density measurements showed that the densification was higher for the ceramic bodies sintered at 1100°C, when compared to the ones calcined at 900°C.