The analyses of frictional losses and thermal stresses in a diesel engine piston coated with different thicknesses of thermal barrier films using co-simulation method

This study comparatively presents the thermal and mechanical effects of different Thermal Barrier Coatings (TBCs) and their thicknesses on the performance of aluminum diesel engine piston by combining Finite Element Analyses (FEA) and Artificial Neural Network (ANN) methods. The piston structure of MWM TbRHS 518S indirect injection six-cylinder diesel engine was modeled. The clustered TBCs (NiCrAlY–Gd2Zr2O7, NiCrAlY–MgO-ZrO2, NiCrAl–Yttria Partially Stabilized Zirconia (YPSZ), and NiCrAlY–La2Zr2O7) were implemented to the related surface of aluminum alloy piston and then static, thermal, and transient structural FEA were conducted for each model. Based on both of the temperature and equivalent stress distributions, NiCrAlY–Gd2Zr2O7 coated model displayed the best performance. Additionally, the effects of top coating thicknesses of TBCs were investigated in the range of 0.1–1.0 mm with 0.1 mm increments in FEAs. The thermally effective top coating thickness was predicted as 0.95 mm for the selected TBC using ANN method. Then the effects of coating thickness on frictional performance were revealed by generating transient structural FE models and utilizing stribeck diagram. The uncoated and 0.95 mm NiCrAlY–Gd2Zr2O7 coated models were adjusted as transient and the related crank angle – dependent in-cylinder combustion pressure data was implemented. The friction force was reduced by at least 15% in NiCrAlY–Gd2Zr2O7 coated model.

Layer-by-Layer Assembled Nano-Composite Multilayer Gas Barrier Film Manufactured with Stretchable Substrate

Most gas barrier films produce cracks that lead to a significant loss of gas barrier integrity when strain is applied. In order to fabricate stretchable gas barrier films with low water permeability and high endurance after stretching, we used polydiallydimethylammonium (PDDA) mixed with graphene oxide (GO) and poly (vinyl alcohol) (PVA) mixed with montmorillonite (MMT). These films were manufactured by layer-by-layer assembly on an Ecoflex/polydimethylsiloxane (PDMS) substrate with pre-strain applied. A total of 30 layers of PDDA (GO)/PVA (MMT) coated on the substrate exhibited a low water vapor transmission rate of 2.5 × 10−2 g/m2 day after 100 cycles of stretching (30% strain). In addition, they exhibited a high light transmittance of 86.54%. Thus, the prepared stretchable gas barrier film has potential applications as a barrier film in transparent and stretchable electronic devices.

Research Progress in the Preparation of Flexible Substrate Barrier Films

The development of flexible electronics towards for the direction of bend ability, lightweight, portability, long life against falling. The performance of the substrate in the flexible electronics plays a very important role in the development of electronics. In this article, three preparation technologies of thin films are introduced, including CVD, PVD and ALD. The paper also introduces the research progress on the preparation of substrate barrier films, and one main challenge that may face by the preparation of thin film materials. In order to satisfy the development of flexible electronics, improving the substrate’s performance constantly is needed. Finally, the development of preparing barrier films is prospected.

Developments in silicone technology for use in stoma care

Soft silicone's flexibility, adhesive capacity and non-toxic, non-odourous and hypoallergenic nature have made it an established material for adhesive and protective therapeutic devices. In wound care, silicone is a component of contact layer dressings for superficial wounds and silicone gel sheeting for reducing the risk of scarring, as well as of barriers for incontinence-associated dermatitis. Regarding stoma accessories, silicone is established in barrier films to prevent contact dermatitis, adhesive removers to prevent skin stripping and filler gels to prevent appliance leaks. Until recently, silicone has not been used in stoma appliances flanges, as its hydrophobic nature has not allowed for moisture management to permit transepidermal water loss and prevent maceration. Traditional hydrocolloid appliances manage moisture by absorbing water, but this can lead to saturation and moisture-associated skin damage (MASD), as well as increased adhesion and resultant skin tears on removal, known as medical adhesive-related skin injury (MARSI). However, novel silicone compounds have been developed with a distinct evaporation-based mechanism of moisture management. This uses colloidal separation to allow the passage of water vapour at a rate equivalent to normal transepidermal water loss. It has been shown to minimise MASD, increase wear time and permit atraumatic removal without the use of adhesive solvents. Trio Healthcare has introduced this technology with a range of silicone-based flange extenders and is working with the University of Bradford Centre for Skin Sciences on prototype silicone-based stoma appliance flanges designed to significantly reduce the incidence of peristomal skin complications, such as MARSI and MASD. It is hoped that this will also increase appliance wear time, reduce costs and improve patient quality of life.