Tensile Strength and Structure of the Interface between a Room-Curing Epoxy Resin and Thermoplastic Films for the Purpose of Sensor Integration

The article presents a study on the adhesion of thermoplastic films to a room temperature-hardening epoxy resin, which deals with an important question on sensor integration into fibre composites. By means of a morphological box, a test specimen is developed, which allows to test strength values for the adhesion of thermoplastic films to epoxy resin. Polyimide (PI), which is typically used as a carrier material for flexible sensors, is compared with the thermoplastics polyetherimide (PEI), polyethersulfone (PES) and polyamide 6 (PA6). To evaluate the spatial formation of the interface, images taken with a light microscope, fluorescence microscope and electron microscope and an energy-dispersive X-ray spectroscopy (EDX) analysis are presented. The images show that during the curing process of the epoxy resin the initially expected pronounced interphase does not form. In this respect, it is surprising that PEI achieves such a high adhesion strength even without extended interphase formation, that the failure of the test specimen occurs in the epoxy resin region at a tensile stress of 70 MPa and not at the interface between epoxy and PEI, as might initially be assumed. It is also surprising that PES exhibits the lowest adhesion strength of 5 MPa to room temperature-hardening epoxy resin, although in previous investigations it was often used as a soluble toughness modifier for epoxy resins. The tensile adhesion strength of PI to epoxy resin was found at 27 MPa and the tensile adhesion strength of PA6 to epoxy resin was found at 13 MPa. For sensor integration, the findings mean that flexible sensors on PEI substrates promise a low tendency to delaminate even in the room temperature-hardening epoxy resin used, while the other materials tested indicate an increased tendency to delaminate.

Effect of Al, Cr, Mo, Zr, Si, and C on the temperature ranges of hardening of multicomponent niobium-based alloys

The effect of alloying and the strain rate on the occurrence and features of the manifestation of temperature ranges in which the strengthening of niobium alloys doped with Ti, Al, Cr, Mo, Zr, Si, C occurs was studied. It was found that in multicomponent solid solutions based on niobium up to sufficiently high temperatures more efficient hardening is provided than in precipitation hardened carbide alloys. It is shown that in multicomponent niobium alloys, which are a solid solution, the selection of alloying can be used to control the manifestation of a high-temperature hardening peak in a wide range. It is possible to change the temperature range of the peak manifestation, its height, sensitivity to the strain rate. The appearance of a high-temperature hardening peak is explained by the loss of stability of the multicomponent solid solution upon deformation in the dislocation field, which leads to the precipitation of dispersed particles of the second phase that pin the dislocations. Keywords: multicomponent niobium alloys, structure, temperature dependence of strength.

Study of the high-temperature hardening zone in Borealis polyethylene

The temperature dependences of tear strength for the main Borealis polyethylene grades were studied. It is shown that along with the common areas where the strength decreases with temperature, there are temperature, regions where the temperature dependence is weakly expressed or there is a maximum tear resistance associated with orientational hardening, similar to the maximum in materials of PE-RT II type.

The Future of the Integral Quench Furnace

Welcome to the 21st Century and the future of the integral quench furnace. The future means safer processing, simple, yet advanced automation, and environmental compliance, all with the proven performance of low pressure processed component parts. The future furnace combines the benefits of low-pressure vacuum carburizing (LPC) technology with atmosphere integral oil quenching. The future means less gas usage, tighter process control, better temperature uniformity, effortless hardening and increased productivity at a highly competitive price point. Added benefits are seamless annealing, normalizing, stress relief, and high temperature hardening processes.

Mechanical properties of welded joints of the pressed aluminum-magnesium 1565Ch alloy at low and high temperatures

The paper studies structure and mechanical properties of welded joints of hot-pressed panels and profiles manufactured by JSC Arkonik SMZ from aluminum-magnesium 1565ch alloy at the temperature range of –165 to 150°C. It is established that the nature of changes in the properties of welded joints of pressed panels and profiles of 1565ch alloy made by manual argon-arc welding with non-consumable electrodes of ArDS with filler material SwAMg-61 at various test temperatures is similar to changes of welded joints of rolled sheets. When the test temperature is lowered, low-temperature hardening of the welded joints takes place – at a cryogenic temperature (–165°C), 20–30% of strength is gained comparing to 20°C. The prolonged aging of welded joints at an elevated temperature (150°C) leads to strength decrease by 25–30% compared to that of 20°C. The coefficient of strength of welded joints with reinforced joint is not less than 0.9 of the actual strength of the base metal at all test temperatures.