Showing papers on "Blisters published in 1975"

Implantation profiles of low‐energy helium in niobium and the blistering mechanism

Abstract: The depth profiles of 1.5–15‐keV 3He ions implanted into a Nb single crystal at doses of 5×1016–7×1018/cm2 have been measured using the 3He (d,p) 4He reaction. A comparison of the results with theoretical predictions for the range and the damage distribution of 3He in amorphous material shows reasonable agreement. Furthermore, the Deckeldicke (i.e., thickness of the covers of the blisters) was determined by Rutherford backscattering in double alignment. The results indicate that stress release rather than explosion of gas bubbles is the dominant mechanism in blister formation.

Correlation between blister skin thickness, the maximum in the damage‐energy distribution, and projected ranges of He+ ions in metals: Nb

Abstract: The skin thicknesses of blisters formed on niobium by helium‐ion irradiation at room temperature for energies from 100 to 1500 keV have been measured. The projected ranges of helium ions in Nb for this energy range were calculated using either Brice’s formalism or the one given by Schiott. For the damage‐energy distribution Brice’s formalism was used. The measured skin‐thickness values corrleate more closely with the maxima in the projected‐range probability distributions than with the maxima in the damage‐energy distributions. The results are consistent with our model for blister formation and rupture proposed earlier.

Formation of blisters in molybdenum bombarded with helium

Abstract: THE formation of surface blisters on metals bombarded with low energy inert gas ions was first observed by Primak1 but only recently, when the potential importance of blistering in the first wall of a fusion reactor became recognised, has much further attention been paid to the phenomenon2,3. Most of this work has used scanning electron microscopy to examine the blistered surface although considerable information has also been obtained from gas release measurements both during bombardment and in post-bombardment anneals. Transmission electron microscopy has been used to a lesser extent but nevertheless has yielded important information on the substructure within the layer where the gas atoms came to rest—normally some hundreds of Angstroms from the metal surface. For example, several workers have shown that gas bubbles form in thin foils irradiated with low energy (<300 keV) helium or argon ions4–6. One interesting fact (D. J. Mazey, unpublished) is that over a wide temperature range from 600 °C down to 20 °C, 36 keV helium bombardment of molybdenum produces a fine distribution of helium bubbles crystallising on to a body-centred-cubic (b.c.c.) lattice analogous to the void lattice4,7. Here I describe an extension of transmission microscopy to view the blisters themselves and suggest some details of the blister formation mechanism.

Friction blisters as a manifestation of pathomimia.

Abstract: Self-inflicted skin lesions (pathomimia, artefacts) can be produced in a variety of ways, by the help of nails, razor blades, cigarettes, chemicals, etc. The present study reports three cases of pathomimia, in which the lesions consisted of vesicles or bullae producted by friction. Friction blisters can easily be produced in sites where the epidermis is both thick and firmly attached to the underlying tissues. The blisters have a characteristic histological appearance, which makes it possible to distinguish them from the blisters of different forms of vesicular and bullous diseases and from burn blisters which may also occur in pathomimia. Language: en

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)

Blister pack having laminated body - with strippable reinforcing cover layer protecting rupturable foil layer

Abstract: Tablets are stored in a blister package which comprises a three layer laminate, the upper layer contg. blisters for holding the tablets. The seal between the bottom and intermediate layers of the laminate has a bond strength less than that existing between the intermediate and upper layer. The bottom layer is of a polymeric plastic which has a tear strength considerably greater than that of the intermediate layer. The upper layer has a peripheral notch associated with each blister and the intermediate layer has a transverse cut adjacent to and spaced from each notch. The package is of a single dosage type and has dosage instructions printed on data layer which overlies the upper layer of the laminate. The integrity of the printed data is not destroyed when a table is removed from the blister. Moreover it is difficult for children to gain access to the tablets.

Facies of ion bombarded surfaces of brittle materials. [Protons, deuterons, He ions]

Abstract: Materials were bombarded by protons, deuterons, and helium ions. The materials investigated were quartz; glasses; carbides and borides (SiC, B/sub 4/C, TiB/sub 2/); oxides and nitrides (magnorite, sapphire, spinel, Al/sub 2/O/sub 3/, Si/sub 3/N/sub 4/, ZrO/sub 2/, BaTiO/sub 3/); and miscellaneous (graphite, LiNbO/sub 3/, copper). Oberservations were of growth, reflectivity, blistering, surface ablation, and swelling. Calculations were made of the effects of a layer, of its gradual transformation, and of the introduction of a gas. It is concluded that: Radiation blistering is not a primary process. Observations of blister formation and exfoliation cannot be used to calculate the surface ablation rate. The primary process is the development of a microporous layer which causes swelling. Visible blisters are caused by fracturing by transverse stresses in this layer and may occur during the bombardment, or in some cases, much later, in storage. There is no evidence of extreme gas pressures in the blisters. When blisters develop, they may be stable under continued bombardment for a dose many times that at which they formed. The swelling is a better index of the effects than is the blistering, and must be associated in most cases with permeability to the gas. Behavior with protons andmore » deuterons is similar, with helium different. All but quartz, vitreous silica, and Pyrex are impervious to hydrogen and deuterium; only dense barium crown glass, carbides, borides, oxides, and nitrides are impervious to helium. Quartz shows swelling caused by conversion to a vitreous product of much lower density but no porosity, while for the others, most of the swelling and surface growth is caused by porosity. Surface ablation by the blistering process may be reduced by initial porosity or by initial or subsequent surface fissuring. However, for impervious materials, surface damage by the introduction of porosity would continue. (DLC)« less

Reduction of surface erosion caused by helium blistering: comparison between vacuum-cast and sintered-beryllium

Abstract: The blister formation and the erosion associated with blistering in a vacuum cast beryllium foil and in a foil of sintered beryllium powder have been investigated for irradiation at room temperature and at 600$sup 0$C with 100 keV $sup 4$He$sup +$ ions for total doses of 0.5 to 1.0 C cm$sup -2$. For room temperature irradiation the blisters in sintered beryllium powder are smaller in size than in vacuum cast beryllium. For irradiation at 600$sup 0$C large scale exfoliation of blisters was observed for vacuum cast beryllium but only small amount of exfoliation was seen for sintered beryllium powder. The results show a reduction in erosion rate in sintered beryllium as compared to the erosion rate in vacuum cast beryllium. For room temperature irradiation no erosion rate could be determined for the sintered beryllium foil since no blister exfoliation was observed. For 600$sup 0$C irradiation the erosion rate for sintered beryllium foil is more than an order of magnitude smaller than for vacuum cast beryllium. (auth)

[The chemotactic effect of blister roof, blister fluid and blister floor on polymorphonuclear leucocytes in dermatitis herpetiformis Duhring (author's transl)].

Abstract: The chemotactic response of polymorphonuclear leucocytes to the blister roof, the blister fluid and the floor of the bulla, the underlying papillary dermis with the basement membrnae, were studied by a modified Boyden-assay in four patients with dermatitis herpetiformis In the same way experimental suction blisters of the peri-lesional skin were investigated The blister roofs showed no chemotactic activity contrary to the blister fluid and especially the underlying papillary dermis which attracted polymorphonuclear leucocytes in a high degree