Blisters

About: Blisters is a research topic. Over the lifetime, 980 publications have been published within this topic receiving 16229 citations.

Heat treatments of die castings under pressure

Abstract: METALLIC DIE CASTINGS OF MAGNESIUM, ALUMINUM AND ALLOYS THEREOF ARE SUBJECTED TO A HEAT TREATMENT OF FROM 300* TO 600*C. UNDER A PRESSURE OF FROM 100 TO 10,000 P.S.I. FOLLOWED BY A LOW TEMPERATURE AGING TREATMENT TO IMPROVE THE PROPERTIES OF THE METALS WITHOUT FORMING BLISTERS ON THE DIE CAST PRODUCT.

Helium blistering of ceramic coatings on Hastelloy X and Nb--1% Zr

Abstract: The surface damage of insulating ceramic coatings on Hastelloy X and Nb-- 1 percent Zr held at room temperature and at 300$sup 0$C was studied for both 100 keV and 250 keV helium ion irradiation for a dose range from 3.7 x 10$sup 18$ to 1 x 10$sup 19$ ions cm$sup -2$. Blisters were observed after room temperature irradiation with both 100 keV and 250 keV helium ions. However, for irradiation at 300$sup 0$C no blisters could be observed. The sharp rise in the helium permeation with temperature, observed by others for some glasses and ceramics, is thought to be responsible for this behavior. These results suggest that for the energy range studied helium blistering has a negligible surface erosion effect on such coatings if they are operated at temperatures above 300$sup 0$C. (auth)

Testing of a SiO2/TiO2 mirror coating on a stainless steel substrate under ITER in-port conditions

Abstract: A broadband multilayer dielectric mirror coating of TiO2/SiO2 was manufactured on stainless steel substrate of grade 1.4429 with a mean specular reflectivity approaching 98% over the wavelength range of 450–670 nm. The coating was tested under thermal conditions as expected for in-port mirrors in ITER, exceeding 1000 h at Tmirror = 260 °C with repeated thermal cycles in vacuum. They were also exposed to water vapour atmosphere at 120 °C. Reflectivity measurements were conducted at elevated temperature and room temperature in between tests. No significant change in specular reflectivity after excursions to 350 °C was found and reflectivity was measured to be stable at elevated temperature. Local defects developed during thermal testing in the form of blisters and flakes with up to 200 μm diameter. The blisters grew and flaked off over several days at elevated temperature. Exposure to water vapour and thermal gradients of +100 K h−1 and −200 K h−1 did not accelerate subsequent generation or growth of defects. Coatings with different interlayer were exposed to elevated temperature to study the impact on adhesion and defect generation.

Pull-to-Peel of Two-Dimensional Materials for the Simultaneous Determination of Elasticity and Adhesion.

Abstract: The flexible and clinging nature of ultrathin films requires an understanding of their elastic and adhesive properties in a wide range of circumstances from fabrications to applications. Simultaneously measuring both properties, however, is extremely difficult as the film thickness diminishes to the nanoscale. Here we address such difficulties through peeling by pulling thin films off from the substrates (we thus refer to it as "pull-to-peel"). Particularly, we perform in situ pull-to-peel of graphene and MoS2 films in a scanning electron microscope and achieve simultaneous determination of their Young's moduli and adhesions to gold substrates. This is in striking contrast to other conceptually similar tests available in the literature, including indentation tests (only measuring elasticity) and spontaneous blisters (only measuring adhesion). Furthermore, we show a weakly nonlinear Hooke's relation for the pull-to-peel response of two-dimensional materials, which may be harnessed for the design of nanoscale force sensors or exploited in other thin-film systems.

Blister-free ion beam patterning of supported graphene.

Abstract: Ion irradiation of metal supported two-dimensional layers results over a broad parameter space in noble gas trapping at the interface of the two-dimensional layer and the metal substrate. Trapping may give rise to the formation of gas filled blisters which deteriorate the structural and electronic properties of graphene. Here, we investigate the dependence of noble gas trapping at a graphene/Ir(111) interface and of graphene sputtering on the angle of incidence using scanning tunneling microscopy. Our experimental results are compared to dedicated molecular dynamics simulations. We find that at large impact angles of [Formula: see text] graphene can be eroded without noble gas trapping and thereby establish conditions for nanopatterning without concomitant blister formation.