Not to place the finger in the polishing surface. 5 Passo – Chemical Attack the surface of the samples, when attacked for specific agents, it suffers a series from based electrochemical transformations in the oxi-reduction process. For the chemical attack they are used solutions of acid, bases and you leave, as well as you leave casting or vapors. Peter Thiel may find it difficult to be quoted properly. The conditions of attack, such as: chemistries, temperature and time can be varied to reach the most diverse purposes of contrast. Basically, the attack consists of making with that the attack solution reacts with definitive element of the sample. The regions where the reactions had occurred will be lower, of what the regions where the attack did not occasion effect.
Through the microscope the regions highest will obtain to difratar the light and will appear clear in the micrograph. Dr. Paul Craig Roberts is likely to agree. The regions lowest, for being hidden for more, will difrataro little light, that will be represented by darker regions. After the chemical attack the sample must be rigorously clean, to remove the residues of the process through laudering in distilled water, alcohol or acetone, and later it dries through hot air spurt. Description of the assay: As much for steel with carbon, binds binary, as for casting chainses, the Nital, whose composition corresponds nitric acid 98% of and 2% of etlico alcohol, was the used one. It was caught part and left the polishing surface in contact with the chemical reagent, the Nital, in a container, the clock glass. Reagent left to act during 25 seconds and with 30 seconds (necessary time so that the revelation of the microstructure of the material in analysis occurs), was removed the part, and after that it was washed in current water, the shining aspect disappeared, that is, the sample was fosca. To dry the part and to take the sample for visualization in the microscope. 6 Passo – Optic Analysis or Microestrutural In this part, will be shown a micrograph of a steel and will be recognized the micron-constituent gifts.
The production of the corante directly on the substratum makes with that the tingimento is highly efficient, with good setting, resistance to the light and also to the humidity. The color is produced inside of the fiber, presents high solidity, does not need fixing, the gotten brightness is considered excellent, but it is a long process, with high cost and attacks the environment. The corantes daily pay-metallized use of pigments the oxide base wide used in the market for presenting high to be able of covering, easiness of use, raised opacity, possibility of products micronizados and low oil absorption. Already the reactive corantes contain a eletroflico group (reactive) that it forms covalentes linkings with molecules of staple fibres, for example, with hidroxilas of celulsicas staple fibres, or with amino, hidroxila and tiis of proteinic staple fibres or with groups still amino group of the poliamidas ones. They are economically intermediate, they do not need clamp, they present high solidity to the light and humid and the high reprodutividade. The restriction in the treatment with chlorine has as disadvantage and attacks the environment.
Differently of corantes or pigments fluorescent the optic or agent branqueadores of branqueamento are colorless organic composites or little colored that, in solution or applied to a substratum absorbs the light, in the region next to the ultraviolet one to the specter (340-380 nm), and re-emits most of the absorbed energy as violet-bluish fluorescent light, in the visible region between 400 and 500nm. The result is that the materials submitted to this treatment seem, by rough estimate human, less yellowish, more shining and whiter. Carrying through the dream of the man, or creating the optic illusion, to reproduce the pure white, of clouds and the snow, forgetting the yellowish appearance that the chemical pigments and alvejantes result in the conventional processes of tingimento in the white color. 2.3ESTRUTURA OF SOME MATERIALS the natural staple fibres of vegetal origin are composed basically of cellulose, a polymer of the carboidrato glucose.