scholarly journals Improved hole wall roughness and corrosion resistance of U-shaped hole prepared by casting

2021 ◽  
Author(s):  
Guanglong Li ◽  
Yang Cao ◽  
Yingdong Qu ◽  
Ruirun Chen ◽  
Rongde Li ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Wall Roughness ◽  
Hole Wall ◽  
Shaped Hole

scholarly journals Improved Hole Wall Roughness and Corrosion Resistance of U-Shaped Hole Prepared by Casting

2021 ◽  
Author(s):  
Yingdong Qu ◽  
Yang Cao ◽  
Guanglong Li ◽  
Ruirun Chen ◽  
Rongde Li ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Water Channel ◽  
Aluminum Matrix ◽  
Cooling Water ◽  
Experimental Temperature ◽  
Wall Roughness ◽  
Cooling Channel ◽  
Hole Wall ◽  
Starting Point ◽  
Shaped Hole

Abstract The corrosion resistance of the cooling water channel in the water-cooled mold has an important impact on the application of the mold. In this paper, the influence of experimental temperature on roughness and corrosion resistance of U-shaped cooling channels prepared by casting is analyzed in detail. The results show that the experimental temperature increased from 998K to 1048K, the hole wall roughness of the U-shaped hole decreased from 83.264 to 76.287. However, the hole wall roughness increased with a further increase in temperature. Because the low experimental temperature will promote the formation of micro bulges and river ripples on the hole wall. However, with the temperature gradually increased, it will promote the aluminum matrix to react with the carbon fiber, which will increase the roughness. The corrosion performance analysis results show that a reasonable experimental temperature is beneficial to reduce the roughness of the hole wall and improve the corrosion resistance of the cooling channel. When the roughness is large, the ravines on the rough surface are easy to be the starting point of corrosion. At the same time, it is easy to cause the aggregation of Si elements to the hole wall at high experimental temperature, which will also cause corrosion. As a result, reasonable experimental temperature plays an important role in improving the corrosion resistance of the U-shaped cooling channel.

Cryogenic auxiliary drilling of printed circuit boards

Circuit World ◽  
2019 ◽  
Vol 45 (4) ◽  
pp. 279-286
Author(s):  
Dantian Lin ◽  
Chengyong Wang ◽  
Lianyu Fu ◽  
Yong Ke ◽  
Yuxing He ◽  
...  
Keyword(s):  
Tool Wear ◽  
Chip Morphology ◽  
Drilling Process ◽  
Wall Roughness ◽  
Cold Air ◽  
Content Type ◽  
Printed Circuit ◽  
Hole Wall ◽  
Capacity Current ◽  
Chip Removal

Purpose Large capacity current carrier printed circuit board (PCB) imposes strict control requirements on the hole wall roughness. The key factors are chip removal, drilling temperature and tool wear. This paper aims to find out a cryogenic drilling process to control the chip removal, chip morphology, tool wear and finally reduce the hole wall roughness. Design/methodology/approach The chip removal process, chip morphology, tool wear and hole wall roughness of glass fiber epoxy resin copper clad laminate (FR-4) drilling were observed and analyzed. The influence of cold air on the chip removal process, chip morphology, tool wear and hole wall roughness was also investigated. An optimization process of cold air auxiliary drilling was proposed to control the hole wall roughness of FR-4. Findings The results showed that the discharge time of copper foil chips with obvious characteristics can be used as the evaluation criterion for the smoothness of chip removal. The cold air can promote chip removal and reduce tool wear. In addition, the chip removal and cooling performance will be the best when using −4.7 °C cold air with the injection angle consisted with the angle of helical flute of the drill. The hole wall roughness of FR-4 could be controlled by drilling with −4.7°C cold air. Originality/value This paper was the first study of the effect of three kinds of cold air on PCB drilling. This provided a reference for the possibility that the cryogenic drilling methods apply to PCB drilling. A new cold air auxiliary drilling process was developed for large capacity current carrier FR-4 manufacturing.

Microstructures of Ti-1.5 w/o Ni Alloys with Mo and A1 Additions

1975 ◽  
Vol 33 ◽  
pp. 54-55
Author(s):  
Anna C. Fraker
Keyword(s):  
Corrosion Resistance ◽  
Beneficial Effect ◽  
Crevice Corrosion ◽  
Local Corrosion ◽  
Precipitate Size ◽  
Ni Alloys

Small amounts of nickel are added to titanium to improve the crevice corrosion resistance but this results in an alloy which has sheet fabrication difficulties and is subject to the formation of large Ti2Ni precipitates. These large precipitates can serve as local corrosion sites; but in a smaller more widely dispersed form, they can have a beneficial effect on crevice corrosion resistance. The purpose of the present work is to show that the addition of a small amount of Mo to the Ti-1.5Ni alloy reduces the Ti2Ni precipitate size and produces a more elongated grained microstructure. It has recently been reported that small additions of Mo to Ti-0.8 to lw/o Ni alloys produce good crevice corrosion resistance and improved fabrication properties.

Role of Aluminium on the Microstructure and Corrosion Behaviour of Magnesium Prepared by Powder Metallurgy Method

2020 ◽  
Vol 17 (3) ◽  
pp. 8206-8213
Author(s):  
J. Alias
Keyword(s):  
Corrosion Resistance ◽  
Powder Metallurgy ◽  
Corrosion Behaviour ◽  
Corrosion Current ◽  
Optical Microscope ◽  
High Reactivity ◽  
Aluminium Content ◽  
Powder Metallurgy Method ◽  
X Ray Diffraction ◽  
Promising Development

Much research on magnesium (Mg) emphasises creating good corrosion resistance of magnesium, due to its high reactivity in most environments. In this study, powder metallurgy (PM) technique is used to produce Mg samples with a variation of aluminium (Al) composition. The effect of aluminium composition on the microstructure development, including the phase analysis was characterised by optical microscope (OM), scanning electron microscopy (SEM) and x-ray diffraction (XRD). The mechanical property of Mg sample was performed through Vickers microhardness. The results showed that the addition of aluminium in the synthesised Mg sample formed distribution of Al-rich phases of Mg17Al12, with 50 wt.% of aluminium content in the Mg sample exhibited larger fraction and distribution of Al-rich phases as compared to the 20 wt.% and 10 wt.% of aluminium content. The microhardness values were also increased at 20 wt.% and 50 wt.% of aluminium content, comparable to the standard microhardness value of the annealed Mg. A similar trend in corrosion resistance of the Mg immersed in 3.5 wt.% NaCl solution was observed. The corrosion behaviour was evaluated based on potentiodynamic polarisation behaviour. The corrosion current density, icorr, is observed to decrease with the increase of Al composition in the Mg sample, corresponding to the increase in corrosion resistance due to the formation of aluminium oxide layer on the Al-rich surface that acted as the corrosion barrier. Overall, the inclusion of aluminium in this study demonstrates the promising development of high corrosion resistant Mg alloys.

The Dependence of Demolding Characteristics on Side Wall Roughness of Mold in Thermal Imprint

2008 ◽  
Vol 128 (8) ◽  
pp. 325-330 ◽  
Author(s):  
Hiroaki Kawata ◽  
Junya Ishihara ◽  
Masayo Kayama ◽  
Masaaki Yasuda ◽  
Yoshihiko Hirai
Keyword(s):  
Side Wall ◽  
Wall Roughness
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