Blisters

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

Non‐destructive indication of delaminations under thick organic coatings using active IR‐thermography

Abstract: The integrity of organic coatings can be impaired by disbondment due to permeation of water vapor in temperature and osmotic gradients between the outer environment and the base metal surface, due to cathodic protection at locally destructed coatings or simply by poor adhesion. For thin coatings the degree of delamination is easily determined by the intensity of blisters which generally arise already after short exposure periods. However, thick coatings with thicknesses above 2 mm take much longer for blistering and larger delaminations, and develop visible blisters only in an advanced state. The degree of delamination is generally detected by mechanical destruction of the coating. The present paper presents a new non-destructive test (NDT) method for detecting delaminations and blisters in or under organic coatings with thicknesses up to 6 mm already at stages when the defects are not yet visible. This is accomplished by active IR thermographic methods with induction and/or optically excited lock-in thermography. The potential of the method is exemplified in this paper for blister determination formed under ΔT-test conditions and for non-destructive quantification of the length of delamination after standardized cathodic disbondment laboratory tests.

Surface damage on stainless steel, Ni, Cu and Mo under mev alpha particle irradiation–surface damage on stainless steel, Ni, Cu, Mo

Abstract: The following kinds of materials, which are potentially useful for CTR construction, namely: the 12KH18N10T, W-4541, W-4016 and SS-304 steels, Ni, Cu and Mo have been Cyclotron irradiated with 3.0, 4.7 and 6.8 MeV He ions with the aim of investigating the energy and the dose dependence of the induced surface deformation effects (blistering and flaking). We report the experimentally determined values for the blisters average diameter and for the critical fluences inducing blistering. We describe other observed features due to irradiation, as sponge-and wave-like structures, submicronic cracks, multilayer flaking, secondary blisters and microcraters. It is discussed the potential validity of the two main categories of explanations which could describe the reported phenomena: the gas driven (gas bubble coalescence) model and the stress-induced model of blistering.

Quantitative evaluation of blisters in polymer-coated steels by three-dimensional optical reconstruction

Abstract: In the industrial application field, the presence of blisters in coated steel is an important quality factor of the protection coating applied on the surface. In this work, an optical system of three-dimensional reconstruction for the detection quantitative evaluation of blisters in polymer coated steel was implemented. The implemented optical system explores a region of 4 x 3 mm with a resolution of 10 μm, using the fringe projection method. The experimental evaluation was realized using six test samples of different protection coating. The test samples were continually exposed to controlled saline atmospheres and they were periodically measured. The presence of first blisters on the surface was determined. Also, the quantitative parameters were measured as maximum height and mean width of blisters, after 566 hours of exposition.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.