Dye penetrant

For a long time, the wheels were mainly tested with dye penetration. This test procedure can make defects which are open to the surface of the material visible for the tester. It is, however, common knowledge that the test results vary greatly depending on the subjective view of the individual tester. 

This paper describes the result obtained in a study of AFCEN (French Society for Design and Construction Rules for Nuclear Island Components) in order to characterize dye penetrant product family, based on experimental test methods of french standards NFA 09.520 and NFA 09.521. In particular, sensitivity tests have been carried out on artificial defects, and correlated with tests on real defects. Some tests on penetrant washability have also been performed. The results obtained with these three series of tests show that the choiee of a dye penetrant product family is not without influency on results obtained, and that is not so simple to make the good choice which could, in certain cases, be the less bad compromise. 

This study has permitted the definition of the minimum requirements to be introduced in RCCM code in order to select properly the dye penetrant product family. 

Klaus Abend "Fully automated Dye-Penetrant Inspection of Automotive Parts", 1998 SAE Int. Congress and Exposition, Detroit 23 - 26 Feb. 1998. 

Monsanto s SEE modacryhc is the only remaining U.S. produced modacryhc flame-tesistant fiber. This fiber is a combination of halogen monomers and a dye receptor to offset the poor dye penetration characteristic of acrylonitrile-vinyl halogen copolymers. 

Dye caiiieis aie needed foi complete dye penetration of polyester fibers. Carriers cause the glass-transition temperature, of the polyester polymer to become lower and allow the penetration of water-insoluble dyes into the fiber. 

Visual identification prior to failure is difficult due to the typical tightness of stress-corrosion cracks. A low-power hand lens will greatly aid determination. Crack enhancement may be achieved through the use of dye penetrants. Severe cracking may be detectable using ultrasonic, radiographic, or acoustic emission techniques. 

Stress-corrosion cracks tend to be fine, tight, and easily overlooked. Various nondestructive techniques are available to aid in the discovery of cracks, such as dye penetrant, and ultrasonic and radiographic techniques. 

Corrosion-fatigue cracks can be detected by nondestructive testing techniques such as magnetic particle inspection, radiography, ultrasonics, and dye penetrant. Corrosion-fatigue cracks may occur in numerous tubes simultaneously. Nondestructive testing of tubes at locations similar to those in which cracks are observed can be useftil. 

Gross cracks may be visually observable. Nondestructive testing for the presence of cracks includes using dye penetrant, ultrasonics, and radiography. Determination of the cracking mechanism will require metallographic analysis. 

Dye penetrant inspection of the hardware to determine the extent of distress in order to develop material requirements and repair techniques. 

The amount of solvent that can be taken into a vessel for dye-penetrant testing or other purposes should be limited so that evaporation of the complete amount will not bring the concentration above the safe concentration, for example, the threshold limit value, making allowance for the air flow if the vessel is force-ventilated. 

Mixtures of liquid oxygen with dichloromethane, 1,1,1-trichloroethane, trichloroethylene and chlorinated dye penetrants 1 and T exploded violently when initiated with a blasting cap. Carbon tetrachloride exploded only mildly, and a partly fluorinated chloroalkane not at all. Trichloroethylene has been used for degreasing metallic parts before use with liquid oxygen, but is not safe. 

Apart from recapture of the injected electrons by the oxidized dye, there are additional loss channels in dye-sensitized solar cells, which involve reduction of triiodide ions in the electrolyte, resulting in dark currents. The Ti02 layer is an interconnected network of nanoparticles with a porous structure. The functionalized dyes penetrate through the porous network and adsorb over Ti02 the surface. However, if the pore size is too small for the dye to penetrate, that part of the surface may still be exposed to the redox mediator whose size is smaller than the dye. Under these circumstances, the redox mediator can collect the injected electron from the Ti02 conduction band, resulting in a dark current (Equation (6)), which can be measured from intensity-modulated experiments and the dark current of the photovoltaic cell. Such dark currents reduce the maximum cell voltage obtainable, and thereby the total efficiency. 

The amount of drawing used depends on (1) the amount of orientation already present from spinning, and (2) the desired level of fiber properties. High levels of final orientation are desired for technical fibers where high tenacity and high initial modulus are needed. Less orientation may be needed for textile fibers, so that dye penetration is faster and the fibers are less stiff. 

The test is based on an in vitro assay of the uptake of the dye, neutral red (NR), in Balb/c 3T3 fibroblasts. It was developed to detect the phototoxicity induced by the combined interaction of the test substance and light of the wavelength range from 315 to 400 nm, the so-called UVA. The cytotoxicity is evaluated in the presence (+UVA) or absence (-UVA) of UVA light exposure, after application of a nontoxic dose of the compound. The cytotoxicological impact is assessed via the inhibition of the fibroblasts to take up the vital dye NR (NR is a weak cationic dye, penetrating easily into the cell membrane by a nonionic diffusion and accumulates in the lysosomes) one day after the initial treatment. Normally, healthy cells may incorporate and bind NR. Alterations of the cell surface or the lysosomal membranes, however, lead to a decreased uptake and binding of the dye. 

Dye penetrant test on the welded surfaces for any blowholes should be conducted before the equipment, pipes and fittings are subjected to hydraulic testing. 

Positive pressure/submersion V acuum/ submersion Dye penetration Vapor/particle leak testing Visual inspection methods Light transmission tests... 

Vacuum/submersion Dye penetration Vapor/particle leak testing... 

When a penetrating colored dye solution is injected into a package it detects channels or voids in the sealed area via capillary action and pinholes in nonporous materials via blotting on a paper tissue. Packs with at least one transparent component are more suitable for viewing the results. Dye penetration is more difficult to use on packages of porous materials, such as paper. 

Absorption of Dyes. In the exhaustion process, the dye is generally absorbed at 60-110°C in 30-60 min, and in the pad steam process at ca. 102-105 °C in 30-60 s. Dyeing with reducing agents is always performed by the exhaustion process. The fixing yield depends greatly on the liquor ratio. Optimal fixation and dye penetration are achieved with the pad roll process, in which the dye is applied from a concentrated liquor. 

If the metal complex dyes carry two sulfo groups, they are suitable for dyeing suede with hair reservation. For full penetration on suede, dyeing starts at a weakly alkaline pH of 8 (mostly adjusted with ammonia), and anionic dye-penetration agents such as naphthalenesulfonic acid-formaldehyde condensate. Finally, the dyes are fixed with an organic acid, preferably formic acid, at a pH of ca. 3.5. 

No particular quench temperature at which crack density increased markedly is observed using dye penetrant for the spinel composites, in contrast to the MgO materials. It is clearly seen that there is a gradual development of a dense microcrack network in the spinel composites, with increase in the quench temperature. 

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