Papers by Keyword: Pinhole

Abstract: To investigate pinholes in 8079 Aluminum foil, optical microscopy and scanning electron microscope with energy dispersive spectrometer were adopted. Results show that four types of pinholes in 8079 aluminum foil, (1) small size, rod-shaped, (2) pinhole in groove, (3) hole with big size, (4) crumpled pinholes. Big compounds along with all rolling and heat treatment processes cause the small rod-shaped pinhole. The big compound contains elements of Al-Fe-O.

Abstract: This paper mainlyintroduces the basic optical principles of light. Using He-Ne laser and pinhole configure collimated illumination, measuring the index of refraction by minimum deviation method, and measuring the birefringence use of wedge method by transmission optical microscope. In addition, give the results and discussion of the whole experiments.

Abstract: Pinhole defects on light gauge aluminum foilwere classified by the morphology characteristics. According to the classification, the formation mechanism of pinhole defects was discussed and some control methods for the control of these pinholes were proposed. and the methods to prevent the pinhole were proposed.

Abstract: During vacuum counter-pressure casting, the vacuumization is an important stage for thin-wall and complicated aluminum alloy castings. Through testing and an analyzing numbers of pinhole and pinhole grade of aluminum alloy samples under different vacuum degree, the effect of vacuum degree on pinhole of vacuum counter- pressure casting molten aluminum alloy is studied. The results indicate vacuum degree has greater effect on pinhole of molten aluminum alloy in vacuumizing process. The smaller vacuum degree is, the more numbers of pinhole of the samples are, and the higher pinhole grade of the samples is. Therefore, when vacuum degree is small, pinhole of molten aluminum alloy appears easily. So the vacuum degree doesn’t choose too small, but for thin-wall and complicated aluminum alloy castings, the vacuum degree doesn’t choose too big either. Appropriate vacuum degree is from 20 KPa to 40 KPa.

Abstract: The decoloration of azo dye (Methyl Orange, MO) by a electrodeless discharge was analyzed. The discharge was generated under and above the pinhole(s) of the insulating plate, which was used to separate the electrodes. The effects of hydroxyl radical scavenger (sodium carbonate) and TiO2 on MO decoloration were studied. The results show that the decoloration rate of MO can be decreased by adding the carbonate ions to the solution, but it will be increased by adding the TiO2. The UV-Vis and FTIR spectras show that the azo bond (-N=N-) of the MO is broken up by corona discharge, and the phenyl-rings is further opened to form small molecular compounds such as organic acid.

Abstract: The impact specimens with different hydrogen contents were solution treated at 540±3°C for 12h; water quenched at 60-100°C; and aged at 165±1°C for 6h. The impact test was carried out at Roell450 pendulum impact testing machine. The impact test results show that the impact energy has strong relation with the hydrogen content. The total absorption energy increases with the increasing of hydrogen content. The crack propagation energy A_vp and present larger proportion than the initial crack energy A_vi in the total absorption energy A_v. The number of the pinholes increases and the pinholes turn from smaller irregular ones into sub-circular shape ones. The specimen with irregular sub-circular pinholes has larger K_I, and has more crack propagation resistance.

Abstract: Authors have reported theses concerning the cast defect for publication in journal of Japanese Foundry Engineering Society and AFS Transactions. This is a review of these reports. There are various factors in the casting defect that occurs in the article of casting metal, and specific of the generation factor is difficult. Moreover, it is necessary to decrease the casting defect to reduce the cost of goods manufactured and energy of production. It is effective to the evaluation and the classification method of the casting defect to employ Scanning Electron Microscopy with Energy Dispersion Spectrometer (SEM-EDS) and Electron Probe Micro-Analysis (EPMA). Casting defects chose the one that the incidence was high and specific of the generation factor is difficult, and the pinhole defect and inclusion defects were classified according to the generation factor, and penetration defect showed the relation of physical factor, chemical factor, and those interactions, and examined whether specific of the factor was possible by the surface analysis equipment about other defects (Blow hole, Shrinkage, Orange peel, Cold shut, Cracks and Veining).

Abstract: CVD diamond layers are often used as protective layers. One of the most important of these applications requires pinhole-free layers to protect against fluid materials, such as found in chemically aggressive environment. These pinholes are present even in very good quality CVD diamond films. In this work we combined the Pulsed Laser Deposition (PLD) technique with Microwave assisted Chemical Vapor Deposition (MW-CVD). We used CVD diamond films prepared under different conditions and layer thicknesses. Both of these proceses produced inperfect protective layers, but we proved that a PLD DLC film over the diamond layer does reduce the number of pinholes in the coating. We used special chemical alcaline etching to detect the remaining pinholes, and to test the corrosion protective properties of the layers. As a result we were able to prepare samples of 1 x 1cm2 with only 0.2 micron thickness without any pinholes, while in CVD diamond layers a thickness of 2,5 micron was needed for the same level of compactness.