The Surface Deformation of Aluminum Compressed With Viscous Lubricants

1974 ◽  
Vol 96 (4) ◽  
pp. 591-594 ◽  
Author(s):  
D. D. Ratnagar ◽  
H. S. Cheng ◽  
J. A. Schey

The influences of lubricant viscosity and loading velocity on the surface finish of plastically compressed 6061 aluminum alloy cylinders were studied. Specimens with polished end faces were subjected to compression between two flat, chromium plated dies, with lubricants of a viscosity ranging from 42 cp to 1207 cp at 38 deg C. The deformed surfaces were studied under a scanning electron microscope and by stylus tracings and CLA readings. With the lighter lubricants surface roughening resulted from preferential yielding leading to a clear delineation of grain boundaries and slip lines. With the heavier lubricants, localized “hydrodynamic pockets” formed in addition to the above features. The depth of pockets increased with viscosity and/or velocity.

2017 ◽  
Vol 47 (8) ◽  
pp. 2029-2049 ◽  
Author(s):  
Siddhan Periyasamy ◽  
Krishna Prasad G ◽  
Raja ASM ◽  
Prashant G Patil

The present study aims to produce submicron surface roughening of aliphatic polyamide 6,6 (nylon 6,6) fabric using dielectric barrier discharge-based atmospheric low temperature plasma for improving the adhesion bonding with rubber. The plasma treatment was done in the time ranging from 15 s to 300 s. Formation of surface roughness on the fabric due to plasma treatment and the associated chemical changes were studied through high-resolution scanning electron microscope, geometrical surface roughness by Kawabata evaluation system surface tester, contact angle measurements and Fourier transform infrared in Attenuated total reflectance mode. Scanning electron microscope micrographs revealed the presence of submicron roughness on the nylon 6,6 fibre surface with pores of around 100 nm (0.1 µm) for the optimum treatment time of 180 s above which the pore merging effect dominated resulting in the net low surface roughness. Geometrical roughness (SMD) results were also well in agreement with the scanning electron microscope results for the roughening and the optimum effect of the plasma treatment. The control and plasma treated nylon 6,6 samples were used as reinforcements for rubber composite. The peel strength of the rubber composite, which is a measure of interfacial bonding, increased to 150% as the maximum for the optimum plasma treatment time of 180 s. Intense rubber deposits over the 180 s plasma treated samples were observed while only a few deposits of rubber were observed on the control fabric when their interfaces were examined through scanning electron microscope after peeling test.


2012 ◽  
Vol 472-475 ◽  
pp. 2756-2759
Author(s):  
Wen Cui ◽  
Shao Jun Qi

To understand the relationship between surface finish and zinc whisker growth, this study investigated the growth of whiskers on two mild steel substrates of different surface finish by Field Emission Gun Scanning Electron Microscope (FEG SEM). Results show that, under the same experimental conditions, deposits on substrates with a mirror finish grew less whiskers and nodules than substrates with a rough surface finish.


2017 ◽  
Vol 88 (1) ◽  
pp. 75-81 ◽  
Author(s):  
Josko Viskic ◽  
Drazen Jokic ◽  
Suzana Jakovljevic ◽  
Lana Bergman ◽  
Sladana Milardovic Ortolan ◽  
...  

ABSTRACT Objective: To evaluate the surface of glazed lithium disilicate dental ceramics after irradiation under different irradiation settings of Nd:YAG and Er:YAG lasers using a scanning electron microscope (SEM). Materials and Methods: Three glazed-press lithium disilicate ceramic discs were treated with HF, Er:YAG, and Nd:YAG, respectively. The laser-setting variables tested were laser mode, repetition rate (Hz), power (W), time of exposure (seconds), and laser energy (mJ). Sixteen different variable settings were tested for each laser type, and all the samples were analyzed by SEM at 500× and 1000× magnification. Results: Surface analysis of the HF-treated sample showed a typical surface texture with a homogenously rough pattern and exposed ceramic crystals. Er:YAG showed no effect on the surface under any irradiation setting. The surface of Nd:YAG-irradiated samples showed cracking, melting, and resolidifying of the ceramic glaze. These changes became more pronounced as the power increased. At the highest power setting (2.25 W), craters on the surface with large areas of melted or resolidified glaze surrounded by globules were visible. However, there was little to no exposure of ceramic crystals or visible regular surface roughening. Conclusions: Neither Er:YAG nor Nd:YAG dental lasers exhibited adequate surface modification for bonding of orthodontic brackets on glazed lithium disilicate ceramics compared with the control treated with 9.5% HF.


2010 ◽  
Vol 97-101 ◽  
pp. 1045-1048
Author(s):  
Zheng Bin Xu ◽  
Yong Zhi Zou ◽  
Wen Chao Wang ◽  
Xing Zhi Pang ◽  
Jian Min Zeng

The scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) were used to characterize samples prepared from the surface scum of melt, the middle flake residues on the furnace wall and the “bottom bulk” after the A357 alloy pouring. The morphology and impurities composition of these features were investigated. Some of particles and regions in samples during the analyses were also studied in detail. The results of analyses show that the surface scum of melt include Al2O3, MgO or MgAl2O4; the impurities of the middle flake residues is comprised of Al2O3, MgO or MgAl2O4, as well as SiO2 particle, Al9Fe2Si2 compound and dimple like C-rich areas; the bottom bulk contains C-rich impurities such as Al4C3 or some of unknown phase or elemental carbon.


Author(s):  
Waris Wibowo

<p>Aluminum alloy 2024-T3 is widely used in manufacturing industries such as aircraft, automotive and ship industries due to its character as a good mechanical property. Aluminum alloy2024-T3, however, is easily suffered from corrosion attack when it is applied in corrosive environment such as sea water. One of the corrosion rate control methods is by applying inhibitor addition. This research aims to study the effect of K2CrO4 inhibitor in controlling the rate of corrosion of Al 2024-T3 in sea water. In this research, K2CrO4 was added to sea water environment with various concentrations of 0.1 %, 0.3% and 0.5%. Subsequently the corrosion rates were measured using a-three-electrode potential technique with saturated calomel (Hg2Cl2) as a referenced electrode whereas the auxiliary electrode was platinum (PT). Fatigue corrosion experiments was done using servo hydraulic testing engine, sinusoidal load was chosen with the stress ratio of R= Smin/Smaks = 0,1, and the frequence of 15 Hz, the voltage level used was 20%. Composition analyses, micro structure examination with Scanning Electron Microscope (SEM) were also done to get the supporting data. The results show that fatigue corrosion rate of aluminum alloy 2024-T3 with the additions of K2CrO4 inhibitor in the sea water tends to reduce at the optimum concentration of 0.5% of K2CrO4. It is indicated by the reduction of fatigue corrosion rate as amount of 32.13%. This inhibitor may hamper the rate of fatigue corrosion by oxidation so that it produces a compound (passive film) which covers the surface of Aluminum alloy 2024-T3 which is in turn it will reduce the attack of corrosion.</p><p><strong>Keywords : Aluminum Alloy 2024-T3, Fatigue Corrosion, K2CrO4 Inhibitor</strong></p><p><br /> ABSTRAK<br /> Aluminium paduan seri 2024-T3 telah banyak diaplikasikan pada industri pesawat terbang, otomotif, dan kapal laut karena memiliki sifat mekanik yang baik. Namun demikian aluminium paduan 2024- T3 rentan terhadap korosi bila diaplikasikan di lingkungan yang korosif seperti air laut. Salah satu upaya untuk mengendalikan laju korosi adalah dengan penambahan inhibitor. Penelitian ini bertujuan untuk mempelajari pengaruh inhibitor kalium kromat (K2CrO4) dalam mengendalikan laju korosi Al 2024-T3 di lingkungan air laut. Pada penelitian ini, jenis inhibitor yang dipakai adalah kalium kromat (K2CrO4) yang ditambahkan di media air laut dengan variasi konsentrasi 0,1%; 0,3%; dan 0,5%. Selanjutnya laju korosi diukur dengan menggunakan metode sel potensial tiga elektroda yang menggunakan kalomel jenuh (Hg2Cl2) sebagai elektroda baku sedangkan elektroda tambahan digunakan platina. Pengujian korosi fatik dengan mesin uji servohidraulik, beban sinusoidal dipilih rasio tegangan R= Smin/Smaks = 0,1 dan frekuensi 15 Hz, level tegangan yang digunakan adalah 20%. Sebagai data pendukung dilakukan uji komposisi dan uji struktur mikro dengan Scanning Electron Microscope (SEM). Hasil penelitian ini memperlihatkan bahwa laju korosi fatik Al 2024-T3 dengan penambahan inhibitor kalium kromat (K2CrO4) di media air laut cenderung menurun pada konsentrasi optimum 0,5% K2CrO4, ditandai dengan penurunan laju korosi fatik sebesar 32,13%. Inhibitor ini dapat menghambat laju korosi fatik dengan cara mengoksidasi sehingga menghasilkan produk senyawa (lapisan pasif) yang dapat menutup permukaan Al 2024-T3 yang dapat mengurangi serangan korosi.</p><p><strong>Kata kunci : Aluminium Paduan 2024-T3, Korosi Fatik , Inhibitor K2CrO4</strong></p><p> </p>


2011 ◽  
Vol 422 ◽  
pp. 627-631 ◽  
Author(s):  
Xie Hua Li ◽  
Li Zi He ◽  
Yi Heng Cao ◽  
Pei Zhu ◽  
Ya Ping Guo ◽  
...  

The influences of cooling rate, hydrogen inflating time, degassing time, inclusion content on the distribution of pores within the ingot , hydrogen content and the mechanical properties of 1050 aluminum alloy were investigated by tensile test, optical microscope(OM), scanning electron microscope(SEM). With the increasing inflating hydrogen time, the hydrogen content increases, while, the strengths and elongation decrease. With the increasing degassing time, the hydrogen content decreases, while, the strengths and the elongation increase. With increasing cast temperature, the hydrogen content remains constant at first and increases obviously from 7200C to 7600C, while the strengths and the elongation decrease gradually. The crack is mainly originated at outcrop of slip step, inclusion and porosity.


2014 ◽  
Vol 511-512 ◽  
pp. 17-21
Author(s):  
Jian Bing Chen ◽  
Chi Peng ◽  
Dong Hai Cheng ◽  
Dong Xu Cheng ◽  
Yi Ping Chen

LF16 aluminum alloy and Q235 steel were brazed by Zn-Al solder and the Al-Si-Cu solder. Metallographic microscope and scanning electron microscope were used to observe the microstructure of weld joint. The result shows that the strength of the joints, which were welded with Zn-Al solder reached 133.6Mpa. Zn-rich solid solution phase and Al-rich solid solution phase existed in Zn-based solder brazing seam. The Fe element trend was gradual changed, while Al element trended more gently, and generated Fe2Al5 intermetallic compounds in the joints in both the brazing joint of Zn-based and Al-based solder.


2016 ◽  
Vol 849 ◽  
pp. 801-806
Author(s):  
Hui Li ◽  
Yi Tan Zhang ◽  
Kei Ameyama ◽  
Hai Jun Yang ◽  
Zhi Guo Liu ◽  
...  

According to the theory of meso-structure design, milling powders were blended with un-milled Al particulate to increase ductility. Two kinds of Al particulate-toughened composites were fabricated by using powder metallurgy method, where the mass fraction of B4C in the B4C-Al agglomerate particles was 40%, but 32% and 16% in the whole composite. The microstructure of composites was examined by scanning electron microscope (SEM), and its mechanical properties were studied. The results indicate that Al particulate-toughened sample has a slight plasticity with bulks of aluminum alloy in the composite. But meso-structure design has no effect on improvement on the plasticity and toughness of the sample B4C-Al/Al (16%)(3#), where the mass fraction of B4C in the whole composite is 16%. In the present study, the strengthening and deformation mechanism of the composites were also discussed.


2014 ◽  
Vol 592-594 ◽  
pp. 489-493 ◽  
Author(s):  
A.V. Santhana Babu ◽  
P.K. Giridharan ◽  
P. Ramesh Narayanan ◽  
S.V.S. Narayana Murty

Limitation in penetration depth is a concern in conventional TIG welding process. To improve penetration capability of TIG process, both Activated TIG (ATIG) and Flux Bounded TIG (FBTIG) are investigated in aluminum alloy AA 2219 T87. Undesirable arc wandering and cracking tendency are observed in ATIG welds. Microstructural investigation reveals ATIG welds are prone for liquation cracks. Morphology of the cracks along with the attributable factors are explained with optical and SEM (Scanning Electron Microscope) micrographs. Energy Dispersive Spectroscopy (EDS) results are also presented to explain the solute enrichment in the grain boundaries of the ATIG welds. FBTIG is found to produce good quality welds and is more suitable for welding aluminum alloys. Key words: Flux Assisted TIG; ATIG; FBTIG; Penetration Improvement; Microstructure; AA2219.


Sign in / Sign up

Export Citation Format

Share Document