Influence of QPQ Treatment on the Corrosion Behavior for Carbon Steel

45 steel was selected as the testing material, QPQ salt bath treatment was conducted by nitriding at the same teperature of 565°C for various time, followed by the same post-oxidation process. Characterization of modified surface layers was made by optical microscopy, X-ray diffraction and corrosion test. The results showed that the cross sectional microstructure was consisted of a thin oxide layer of Fe3O4 at the external surface formed during post-oxidation, a bright zone of εnitrides at the subsurface formed during nitriding and a diffusion zone related to the core. The corrosion resistance of 45 steel in hot water can be significantly improved by QPQ complex salt bath treatment, and the suitable duration of nitriding and post-oxidation to improve the corrosion resistance was 90min and 100min, respectively.

Download Full-text

COMPARISON OF SALT BATH PREOXIDATION AND AIR PREOXIDATION FOR SALT BATH NITRIDING

Acta Metallurgica Slovaca ◽

10.12776/ams.v25i2.1271 ◽

2019 ◽

Vol 25 (2) ◽

pp. 130

Author(s):

Wenchen Mei ◽

Jiqiang Wu ◽

Mingyang Dai ◽

Kunxia Wei ◽

Jing Hu

Keyword(s):

Compound Layer ◽

Salt Bath ◽

Micro Hardness ◽

X Ray Diffraction ◽

X Ray ◽

Hardness Tester ◽

Modified Surface ◽

Salt Bath Nitriding ◽

Modified Surface Layer

<p class="AMSmaintext1">Salt bath preoxidation was primarily conducted prior to salt bath nitriding, and the effect on salt bath nitriding was compared with that of conventional air preoxidation. Characterization of the modified surface layer was made by means of optical microscopy, scanning electron microscope (SEM), micro-hardness tester and x-ray diffraction (XRD). The results showed that the salt bath preoxidation could significantly enhance the nitriding efficiency. The thickness of compound layer was increased from 13.3μm to 20.8μm by salt bath preoxidation, more than 60% higher than that by conventional air preoxidation under the same salt bath nitriding parameters of 560℃ and 120min. Meanwhile, higher cross-section hardness and thicker effective hardening layer were obtained by salt bath preoxidation, and the enhancement mechanism of salt bath preoxidation was discussed.</p>

Download Full-text

Characterization of Micro-Arc Oxidation Coatings Formed on Biomedical Ni-Cr-Mo Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.337.29 ◽

2011 ◽

Vol 337 ◽

pp. 29-32

Author(s):

Ji Lin Xu ◽

De Zhen Yu ◽

Jun Ming Luo

Keyword(s):

Corrosion Resistance ◽

Coated Sample ◽

X Ray Diffraction ◽

Cross Sectional ◽

X Ray ◽

Ni Content ◽

Polarization Test ◽

Micro Arc Oxidation ◽

Chemical And Phase Compositions

In this paper, the micro-arc oxidation coatings formed on biomedical Ni-Cr-Mo alloy were characterized by surface and cross-sectional morphologies, chemical and phase compositions and corrosion resistance using scanning electron microscopy (SEM), Energy dispersive X-ray spectrometer (EDS), X-ray diffraction (XRD) and potentiodynamic polarization test, respectively. The results show that the coating is mainly composed of γ-Al2O3 crystal phase with a little Ni content. The coating possesses a typical porous surface and has a thickness of ~6 μm. The corrosion resistance of the coated sample is greatly improved compared with the uncoated Ni-Cr-Mo alloy.

Download Full-text

Influence of QPQ Salt Bath Composite Processing on Microstructure and Property of a Certain Type Aviation Piston Engine Ring

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.751.26 ◽

2015 ◽

Vol 751 ◽

pp. 26-29

Author(s):

Jun Wen Lu ◽

Qian Ying Wang ◽

Bo Zheng

Keyword(s):

Wear Resistance ◽

Hardness Test ◽

Complex Salt ◽

Compound Layer ◽

Salt Bath ◽

Micro Hardness ◽

Piston Engine ◽

Untreated Sample ◽

Modified Surface

QPQ salt bath treatment of a certain type aviation piston engine ring was conducted by nitriding (570°C, 180 min), followed by the post-oxidation process (400°C, 20 min), polishing, the second post-oxidation (370°C, 20 min). Characterization of modified surface layers was made by means of optical microscopy, micro-hardness test, corrosion and wear resistance test. The results showed the formation of a very thin oxide layer during post-oxidation on the top of the black nitrides compound layer formed during nitriding. The maximum micro-hardness value of 592 HV was obtained after nitriding at 570°C for 180 min, which was nearly twice higher than that of the untreated sample. The wear resistance of ring could be significantly improved by QPQ complex salt bath treatment, which is almost 5 times higher than that of the untreated sample.

Download Full-text

Surface Modification of a Nickel-Free Austenitic Stainless Steel by Low-Temperature Nitriding

Metals ◽

10.3390/met11111845 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1845

Author(s):

Francesca Borgioli ◽

Emanuele Galvanetto ◽

Tiberio Bacci

Keyword(s):

Stainless Steel ◽

Corrosion Resistance ◽

Austenitic Stainless Steel ◽

Low Temperature ◽

Stainless Steels ◽

Volume Fraction ◽

Surface Hardness ◽

Austenitic Stainless Steels ◽

Surface Layers ◽

Modified Surface

Low-temperature nitriding allows to improve surface hardening of austenitic stainless steels, maintaining or even increasing their corrosion resistance. The treatment conditions to be used in order to avoid the precipitation of large amounts of nitrides are strictly related to alloy composition. When nickel is substituted by manganese as an austenite forming element, the production of nitride-free modified surface layers becomes a challenge, since manganese is a nitride forming element while nickel is not. In this study, the effects of nitriding conditions on the characteristics of the modified surface layers obtained on an austenitic stainless steel having a high manganese content and a negligible nickel one, a so-called nickel-free austenitic stainless steel, were investigated. Microstructure, phase composition, surface microhardness, and corrosion behavior in 5% NaCl were evaluated. The obtained results suggest that the precipitation of a large volume fraction of nitrides can be avoided using treatment temperatures lower than those usually employed for nickel-containing austenitic stainless steels. Nitriding at 360 and 380 °C for duration up to 5 h allows to produce modified surface layers, consisting mainly of the so-called expanded austenite or gN, which increase surface hardness in comparison with the untreated steel. Using selected conditions, corrosion resistance can also be significantly improved.

Download Full-text

Effect of QPQ Salt Bath Oxidation on Corrosion Resistance

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.118.209 ◽

2006 ◽

Vol 118 ◽

pp. 209-214

Author(s):

Yuan Hui Li ◽

De Fu Luo ◽

Shao Xu Wu

Keyword(s):

Corrosion Resistance ◽

Water Solution ◽

Salt Spray ◽

Complex Salt ◽

Salt Bath ◽

Neutral Solution ◽

High Corrosion Resistance ◽

Salt Bath Nitriding ◽

Porous Area ◽

Magnetite Film

The QPQ complex salt bath treatment is a type of surface technology which contains mainly salt bath nitriding and post-oxidizing processes. The effect of QPQ oxidizing temperature and duration on the corrosion resistance of QPQ treated specimens has been explored by immersion tests and salt spray tests in this paper. All the specimens were post-oxidized after being nitrided at 570! for 2 hours. The material used in this study were 1020 steel. In the immersion tests, the specimens were immersed in 3‰ H2O2 and 10% NaCl water solution. In the salt spray tests, specimens were salt spray tested using 5% NaCl neutral solution. From the experimental data, for high corrosion resistance, conclusions can be drawn:(1) appropriate temperature should be selected carefully in post-oxidizing stage .Too low or too high temperature would decrease the corrosion resistance. (2) The best post-oxidizing duration should generate magnetite film in porous area and should not collapse. (3) In second oxidizing stage, the porous area has been partly eliminated, so the duration should be less than the duration of post-oxidizing.

Download Full-text

Characterization of the Surface Layer of Mg Enriched with Al and Si by Thermochemical Treatment

Archives of Foundry Engineering ◽

10.1515/afe-2017-0157 ◽

2017 ◽

Vol 17 (4) ◽

pp. 195-199 ◽

Cited By ~ 1

Author(s):

R. Mola ◽

E. Stępień ◽

M. Cieślik

Keyword(s):

Solid Solution ◽

Thermochemical Treatment ◽

Heating Time ◽

Substrate Material ◽

Surface Layers ◽

X Ray ◽

Three Phase ◽

Distribution Of Elements ◽

Modified Surface

AbstractThe modified surface layers of Mg enriched with Al and Si were fabricated by thermochemical treatment. The substrate material in contact with an Al + 20 wt.% Si powder mixture was heated to 445°C for 40 or 60 min. The microstructure of the layers was examined by OM and SEM. The chemical composition of the layer and the distribution of elements were determined by energy dispersive X-ray spectroscopy (EDS). The experimental results show that the thickness of the layer is dependent on the heating time. A much thicker layer (1 mm) was obtained when the heating time was 60 min than when it was 40 min (600 μm). Both layers had a non-homogeneous structure. In the area closest to the Mg substrate, a thin zone of a solid solution of Al in Mg was detected. It was followed by a eutectic with Mg17Al12and a solid solution of Al in Mg. The next zone was a eutectic with agglomerates of Mg2Si phase particles; this three-phase structure was the thickest. Finally, the area closest to the surface was characterized by dendrites of the Mg17Al12phase. The microhardness of the modified layer increased to 121-236 HV as compared with 33-35 HV reported for the Mg substrate.

Download Full-text

Characterization and Tribological Performance of Cu-Based Intermetallic Layers

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.533.195 ◽

2012 ◽

Vol 533 ◽

pp. 195-200 ◽

Cited By ~ 1

Author(s):

J. Joseph ◽

Daniel M. Fabijanic

Keyword(s):

Chemical Vapor ◽

High Hardness ◽

Optical Emission ◽

Wear Testing ◽

X Ray Diffraction ◽

Surface Layers ◽

Pin On Disc ◽

Titanium Silicon ◽

Backscatter Scanning Electron Microscopy

Fluidized bed reactor chemical vapor deposition (FBR-CVD) has been used to enrich the surface of oxygen free high conductivity (OFHC) copper with titanium, silicon and aluminum. This technique enables the production of coherent and adherent intermetallic surface layers of uniform thickness and high hardness. The characterization of the coatings was performed using backscatter scanning electron microscopy (BS-SEM), X-ray diffraction (XRD), glow discharge optical emission spectroscopy (GDOES) and micro-hardness. The tribological properties of the coatings in dry sliding contact with steel were evaluated by pin-on-disc wear testing.

Download Full-text

Epitaxial growth and characterization of BP on Si(100) substrate for use in c-GaN study

MRS Proceedings ◽

10.1557/proc-0891-ee03-14 ◽

2005 ◽

Vol 891 ◽

Author(s):

Tomohiko Takeuchi ◽

Suzuka Nishimura ◽

Tomoyuki Sakuma ◽

Satoru Matumoto ◽

Kazutaka Terashima

Keyword(s):

Epitaxial Layer ◽

Careful Analysis ◽

X Ray Diffraction ◽

Si Substrate ◽

Cross Sectional ◽

X Ray ◽

Si Substrates ◽

Impurity Doping ◽

Hall Effect Measurements

ABSTRACTBoronmonophosphide(BP) is one of the suitable materials for a buffer layer between the c-GaN(100) and Si(100) substrates. The growth of BP layer was carried out by MOCVD on Si(100) substrate of 2 inch in diameter. The growth rate was over 2 μm/h without any troubles such as the bowing or cracking. In addition, the thickness of BP epitaxial layer was uniform over a wide area. A careful analysis of x-ray diffraction suggested that the growth of BP epitaxial layer inherited the crystal orientation from Si(100) substrate. Cross-sectional TEM images showed some defects like dislocations near the interface between BP layer and Si substrate. The Hall effect measurements indicated that the conduction type of BP films grown on the both n-Si and p-Si substrates was n-type without impurity doping, and that the mobility and carrier concentrations were typically 357cm2/Vs and 1.5×1020cm−3(on n-Si) and 63cm2/Vs and 1.9×1019cm−3(on p-Si), respectively. In addition, c-GaN was grown on the substrate of BP/Si(100) by RF-MBE.

Download Full-text

Glass-Forming Ability and Crystallization Kinetics of Hf-Ti-Cu-Ni-Al Bulk Metallic Glass

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.479-481.1786 ◽

2012 ◽

Vol 479-481 ◽

pp. 1786-1789 ◽

Cited By ~ 1

Author(s):

Tie Jun Chen

Keyword(s):

Thermal Stability ◽

Crystallization Kinetics ◽

Glass Formation ◽

Glass Forming Ability ◽

Ideal Condition ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

Cross Sectional ◽

Glass Forming

Multi-component Hf45.6Cu27.8Ni9.3Ti5Al12.4bulk metallic glasses (BMGs) were prepared successfully by casted into the water-cooled Cu mold. Characterization of the casted Hf45.6Cu27.8Ni9.3Ti5Al12.4rods was carried out by X-ray diffraction. The thermal stability and crystallization kinetics were followed by differential scanning calorimetry. The results show that the alloy Hf45.6Cu27.8Ni9.3Ti5Al12.4had a critical cylindrical rod diameter for glass formation, Dc, of 7 mm and the largest cross-sectional diameter (about 12.4mm) can be obtained in the ideal condition. The critical cooling rate for glass formation is 6.48K/s. The Hf45.6Cu27.8Ni9.3Ti5Al12.4BMG has larger glass forming ability and higher thermal stability.

Download Full-text