scholarly journals Energy Density Effect of Laser Alloyed TiB2/TiC/Al Composite Coatings on LMZ/HAZ, Mechanical and Corrosion Properties

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 411
Author(s):  
Dunja Ravnikar ◽  
Uroš Trdan ◽  
Aleš Nagode ◽  
Roman Šturm
Keyword(s):  
Laser Energy ◽  
Composite Coatings ◽  
Corrosion Current ◽  
Al Alloy ◽  
Alloy Sample ◽  
Corrosion Properties ◽  
Cyclic Polarization ◽  
Al Composite ◽  
General Improvement ◽  
High Fraction

In the present work, TiC/TiB2/Al composite coatings were synthesized onto a precipitation hardened AlSi1MgMn alloy by laser surface alloying (LSA), using 13.3 J/mm2 and 20 J/mm2 laser energy densities. Microstructure evaluation, microhardness, wear and corrosion performance were investigated and compared with the untreated/substrate Al alloy sample. The results confirmed sound, compact, crackles composite coating of low porosity, with a proper surface/substrate interface. Microstructural analyses revealed the formation of extremely fine nano-precipitates, ranging from of 50–250 nm in the laser melted (LMZ) and large precipitates, accompanied with grain coarsening in the heat-affected zone (HAZ), due to the substrate overheating during the LSA process. Nonetheless, both coatings achieved higher microhardness, with almost 7-times higher wear resistance than the untreated sample as a consequence of high fraction volume of hard, wear resistant TiB2 and TiC phases inside the composite coatings. Further, cyclic polarization results in 0.5 M NaCl aqueous solution confirmed general improvement of corrosion resistance after LSA processed samples, with reduced corrosion current by more than a factor of 9, enhanced passivation/repassivation ability and complete prohibition of crystallographic pitting, which was detected with the untreated Al alloy.

Effect of the Ceramic Dispersion in the Nickel Matrix Composite Coatings on Corrosion Properties after Plastic Working

2011 ◽  
Vol 183 ◽  
pp. 43-48 ◽  
Author(s):  
Tomasz Cyryl Dyl ◽  
Robert Starosta
Keyword(s):  
Surface Roughness ◽  
Composite Coatings ◽  
Alloy Coating ◽  
Corrosion Current ◽  
Hydraulic Press ◽  
Flame Spraying ◽  
Al Alloy ◽  
Plastic Working ◽  
Corrosion Properties ◽  
Dispersion Phase

Coatings of metal and ceramic composite were applied on the steel specimens using the subsonic process of flame spraying. The specimens were then subjected to both cold and hot plastic working by rolling and also cold pressing by the hydraulic press. Plastic working is an alternative to machining, as the method of finishing of coats applied by flame spraying. The article presents the findings of the research into the possibility of using plastic working (hot and cold rolling and pressing) to obtain the corrosion properties of the flame sprayed Ni-Al alloy coatings and Ni-Al-Al2O3composite coatings. The alloy coatings had a single-phase structure, of the maximum 10% aluminium solubility in the crystal lattice of nickel, whereas in the composite coatings the volume content of non-metallic material Al2O3was 15% and 30 %. After finishing the adhesion reduction, cracks on the surface and cross-sections of coatings was not observed. The largest value of strain hardening of alloy coating Ni-5%Al was stated after pressing. The composite coatings obtain by flame spraying be characterized by big surface roughness (Ra= 13.3 µm). The plastic working caused decrease surface roughness. Minimum value of Raparameter was observed after hot rolling. It was found that maximal roughness was presented after pressing. The corrosion tests were performed in 0.01 M H2SO4solution by potentiokinetic technique. The article presents the effect of dispersion phase of Al2O3on corrosion properties of composite coatings on the nickel base. The corrosion rate was dependent on method of plastic working. The increasing drafts resulted in rise corrosion current density and decrease in value of corrosion potential.

Corrosion of Ni-Al and Ni-Al-Al2O3 Flame Sprayed Coatings of „CastoDyn 8000" System in 0.01 M H2SO4 and 3.5% NaCl Solutions

2011 ◽  
Vol 183 ◽  
pp. 185-192 ◽  
Author(s):  
Robert Starosta
Keyword(s):  
Current Density ◽  
Corrosion Current Density ◽  
Sea Water ◽  
Composite Coatings ◽  
Corrosion Current ◽  
Artificial Seawater ◽  
Flame Spraying ◽  
Al Alloy ◽  
Acidic Environment ◽  
Corrosion Properties

In the paper researches results of corrosion properties of Ni-Al alloy and Ni-Al-Al2O3 composite coatings were presented. Coatings were obtained by flame spraying of "Casto-Dyn 8000" torch. During coatings flame spraying of torch was used a small distance from the substrate. Instead of commonly used spray distance 150 mm, 100 mm was used. The studies in 0.01 M H2SO4 and 3.5% NaCl (artificial seawater) environments were realized. Evaluated coatings are more corrosion resistant in the 3.5% NaCl environment than in the 0.01 M H2SO4. Corrosion current density for alloy coatings in artificial seawater was 20 μA/cm2 and 223 μA/cm2 in an acidic environment. The value of corrosion potential in an environment of 3.5% NaCl is about 200 mV lower than in 0.01 M H2SO4. Composite coatings Ni-Al-Al2O3 were characterized by a lower corrosion current densities and increased resistance than Ni-Al coatings in acidic environment. The presence of alumina in the coating matrix caused increased corrosion current density in sea water environment.

Corrosion of Ni-Al and Ni-Al-Al2O3 Plasma Sprayed Coatings in 0.01 M H2SO4 and 3.5% NaCl Solutions

2013 ◽  
Vol 199 ◽  
pp. 390-395
Author(s):  
Robert Starosta
Keyword(s):  
Impedance Spectroscopy ◽  
Current Density ◽  
Corrosion Current Density ◽  
Corrosion Potential ◽  
Composite Coatings ◽  
Corrosion Current ◽  
Charge Transfer Resistance ◽  
Al Alloy ◽  
Corrosion Properties ◽  
Transfer Resistance

In the paper researches results of corrosion properties of Ni-Al alloy and Ni-Al-Al2O3 composite coatings were presented. Coatings were obtained by plasma torch. The studies in 0.01 M H2SO4 and 3.5 NaCl environments were realized. Measurements were made following methods: polarization and impedance spectroscopy. Rated coatings are more resistant to the 3.5% NaCl environment than the 0.01 M H2SO4. Corrosion current density for alloy coatings in artificial seawater was 19 μΑ/cm2 and 28 μA/cm2 environment acidic. Impedance spectroscopy studies showed that the alloy and composite coatings are characterized by greater charge transfer resistance in sodium chloride solution than in sulfuric acid solution. The value of corrosion potential in an environment of 3.5% NaCl is about 300 mV lower than 0.01 M H2SO4. Composite coatings Ni-Al-Al2O3 were characterized by a higher corrosion current densities and increased resistance than Ni-Al coatings in 0.01 M H2SO4 solution. It is related to the porosity of composite coatings. It was found little effect of oxide phase participation on corrosion current density and corrosion potential in 3.5% NaCl environment.

Composite Coatings Formed on PEO Pretreated MA8 Magnesium Alloy in Aqueous Suspension of PTFE

2021 ◽  
Vol 885 ◽  
pp. 95-102
Author(s):  
Evgeny A. Belov ◽  
Konstantine V. Nadaraia ◽  
Dmitry V. Mashtalyar ◽  
Igor M. Imshinetsky ◽  
Andrey P. German ◽  
...  
Keyword(s):  
Composite Coatings ◽  
Aqueous Suspension ◽  
Corrosion Current ◽  
Composite Polymer ◽  
Corrosion Properties ◽  
Composite Layers ◽  
Electrolytic Oxidation ◽  
Subsequent Application ◽  
Plasma Electrolytic ◽  
Scratch Tests

The paper presents results of the composite polymer-containing layers formation by plasma electrolytic oxidation (PEO) with subsequent application of the superdispersed polytetrafluoroethylene (SPTFE) aqueous suspension. The corrosion properties and adhesion of coatings have been investigated using potentiodynamic polarization and scratch tests. Incorporation of SPTFE decreased the corrosion current density for composite layers by more than 3 orders of magnitude in comparison with the base PEO-coating and increased the coatings adhesion by 30 %.

Structural Characterization and Corrosion Properties of BTESPT Silane Films on Surface of 2024-T6 Aluminium Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 1111-1116 ◽  
Author(s):  
Ming An Chen ◽  
Xuan Xie ◽  
Guo Fu Xu ◽  
Hui Zhong Li ◽  
Xin Ming Zhang
Keyword(s):  
Structural Characterization ◽  
Water Solution ◽  
Corrosion Current ◽  
Immersion Test ◽  
Alloy Sheet ◽  
Al Alloy ◽  
Entire Surface ◽  
Corrosion Properties ◽  
The Matrix

2024-T6 Al alloy sheet s were modified by bis-[triethoxysilylpropyl] tetrasulfide (BTESPT) silane film to improve the corrosion resistance. Fourier-Transform Reflection Absorption (FTIR-RA) spectroscopy was used for structural characterization of BTESPT silane film formed on surface of the sheet. Potentiodynamic polarization and immersion test in 3.5% NaCl solution were used for evaluating the corrosion performances of the silane film. The results showed that the film formed after curing at 120 °C for 40 min was cross-linked through Si-O-Si and that it was covered on the entire surface of the sheet. The content of elements S and Si on the Al2CuMg particles is a little higher that of on the matrix. The strong peak at 1032 cm-1 indicated that the film was linked to the sheet by Si-O-Al. Compared to the untreated case, the corrosion current density of the sheet treated with the silane film was reduced by close to 2 orders. Treatment of BTESPT silane can provide about 670 h protection of corrosion for the sheet in 3.5% NaCl water solution.

Fabrication and Characterization of Hydroxyapatite-Magnesium Composite Thin Films on Magnesium Plates for Implant Applications

2012 ◽  
Author(s):  
Kwadwo Mensah-Darkwa ◽  
Ram K. Gupta ◽  
Dhananjay Kumar
Keyword(s):  
Thin Films ◽  
Potentiodynamic Polarization ◽  
Composite Coatings ◽  
Composite Films ◽  
Corrosion Current ◽  
Biological Properties ◽  
Cytotoxicity Test ◽  
Corrosion Properties ◽  
Composite Thin Films ◽  
X Ray

Hydroxyapatite (HA)-magnesium (Mg) composite thin films were grown on magnesium substrates using a multitarget pulsed laser deposition technique. The microstructural and corrosion properties of HA-Mg composite thin films were investigated using methods such as x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray (EDX) analysis, and potentiodynamic polarization. While the XRD studies have indicated the amorphous nature of the HA-Mg composite coating, SEM and EDX studies have shown that the composite films are stoichiometric. The potentiodynamic polarization study indicates that the corrosion of magnesium decreases with increase in the hydroxyapatite content in the composite film. The corrosion potential (Ecorr) and corrosion current density (Icorr) for the uncoated magnesium, 30HA-70Mg, and 50HA-50Mg coated magnesium are −1.59, −1.57, −1.54 V and 1.21×10−5, 1.38×10−6, 2.52×10−7 A/cm2, respectively. Preliminary cytotoxicity test conducted on the samples shows no adverse effect on human bone marrow stromal cells. The advantage of the composite coatings is the realization of adjustable corrosion and biological properties by a simple maneuvering of composition which in turn is realized by changing the number of laser pulses on a respective target.

Diffraction study on bainite of Cu-Al alloy

1990 ◽  
Vol 48 (4) ◽  
pp. 1006-1007
Author(s):  
Delu Liu ◽  
T. Ko
Keyword(s):  
Diffraction Study ◽  
Parent Phase ◽  
Al Alloy ◽  
Alloy Sample ◽  
Bright Field Image ◽  
Hexagonal System ◽  
Iced Brine ◽  
Diffraction Patterns ◽  
Zone Pattern ◽  
Stacking Structure

Structure of bainite in Cu-Al and Cu-Zn-Al alloys has been reported as 3R, 9R or 18R long period stacking structure (LPS) by X-ray and electron diffraction studies. In the present work, a Cu-25.5 (at)% Al alloy sample was heated at 900°C for 2 h then isothermally held at 450°C for 60 s before quenching into iced brine. FIG.1 shows a TEM bright field image of bainite plates (marked B) grown from grain boundary. The parent phase ( with DO3 structure ) has transformed to martensite (marked M ) during cooling from 450° C to 0°C. Both bainite and martensite plates have dense striations inside.Careful diffraction study on a JEOL 2000FX TEM with accelerating voltage 200 KV revealed (FIG.2) that the diffraction patterns contai_ning the same zone axis [001] ( hexagonal index ) or [111]c ( cubic index ) are from a bainite plate with obtuse V-shape. They are indexed as [010], [140], [130], [120], [230], [340] and [110] zone pattern for hexagonal system respectively.

scholarly journals Using Graphene-Based Composite Materials to Boost Anti-Corrosion and Infrared-Stealth Performance of Epoxy Coatings

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1603
Author(s):  
Meng-Jey Youh ◽  
Yu-Ren Huang ◽  
Cheng-Hsiung Peng ◽  
Ming-Hsien Lin ◽  
Ting-Yu Chen ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Graphene Nanosheets ◽  
Salt Spray ◽  
Corrosion Current ◽  
Filler Concentration ◽  
Epoxy Coatings ◽  
Corrosion Properties ◽  
Water Contact ◽  
Different Temperatures ◽  
Thermal Signature

Corrosion prevention and infrared (IR) stealth are conflicting goals. While graphene nanosheets (GN) provide an excellent physical barrier against corrosive agent diffusion, thus lowering the permeability of anti-corrosion coatings, they have the side-effect of decreasing IR stealth. In this work, the anti-corrosion properties of 100-μm-thick composite epoxy coatings with various concentrations (0.01–1 wt.%) of GN fillers thermally reduced at different temperatures (300 °C, 700 °C, 1100 °C) are first compared. The performance was characterized by potentiodynamic polarization scanning, electrochemical impedance spectroscopy, water contact angle and salt spray tests. The corrosion resistance for coatings was found to be optimum at a very low filler concentration (0.05 wt.%). The corrosion current density was 4.57 × 10−11 A/cm2 for GN reduced at 1100 °C, showing no degradation after 500 h of salt-spray testing: a significant improvement over the anti-corrosion behavior of epoxy coatings. Further, to suppress the high IR thermal signature of GN and epoxy, Al was added to the optimized composite at different concentrations. The increased IR emissivity due to GN was not only eliminated but was in fact reduced relative to the pure epoxy. These optimized coatings of Al-GN-epoxy not only exhibited greatly reduced IR emissivity but also showed no sign of corrosion after 500 h of salt spray test.

Sign in / Sign up

Export Citation Format

Share Document