Curing of inorganic composition coating of aluminum – phosphate system

2020 ◽  
Vol 25 (2) ◽  
pp. 26-33
Author(s):  
S.A. Demin ◽  
A.P. Petrova
Keyword(s):  
Heat Treatment ◽  
Composite Coating ◽  
Potassium Phosphate ◽  
Aluminum Phosphate ◽  
Large Structures ◽  
Recent Developments ◽  
Poorly Soluble ◽  
Prolonged Heat ◽  
Phosphate System ◽  
Inorganic Composite

Known methods for applying an inorganic composite coating are accompanied by its heat treatment at a temperature of at least 300 °C, which requires the use of furnaces. Recent developments have allowed to reduce the temperature of heat treatment to 90 °C for at least 3 hours or to 105 °C for at least 1 h, which allows the use of portable heating equipment. However, the use of any equipment with such prolonged heat treatment is not acceptable when applying corrosion protection to large structures, especially when their dismantling is impossible. The results of studies on the chemical curing of an inorganic composite coating that does not require heat treatment are presented. It is proposed to spray a hardener solution onto a composite coating having a more alkaline pH instead of heat treatment. When a hardener reacts with acidic residues of an inorganic binder on the surface of a dried coating, monosubstituted phosphates undergo a transition to poorly soluble two-and practically insoluble tri-substituted phosphates not only on the coating surface, but also on the inner surface of the pores, which leads to almost complete insolubility of the coating. Treatment of the coating with an aqueous solution of monosubstituted potassium phosphate, two-substituted potassium phosphate or potassium pyrophosphate gives the coating water resistance. The inorganic composite coating acquires a high protective ability (more than 1300 hours in a salt fog chamber) on steel parts after treatment with only aqueous solutions of mono-substituted or two-substituted potassium phosphate.

Phase Evolution of Aluminum-Chromium-Phosphate Binders during Heat-Treatment

2007 ◽  
Vol 336-338 ◽  
pp. 1280-1283 ◽  
Author(s):  
Chao Zou ◽  
Da Hai Zhang ◽  
Yi Li ◽  
Wen Jian Weng ◽  
Kui Cheng ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Amorphous Phase ◽  
Chromium Oxide ◽  
Phase Evolution ◽  
Aluminum Phosphate ◽  
Phosphate Binders ◽  
Amorphous Network ◽  
Phosphate System ◽  
Chromium Phosphate

Aluminum phosphate is one of the best inorganic binders, and the addition of chromium oxide can improve the properties of the binder. In this work, the phase evolutions in chromium phosphate system and aluminum-chromium-phosphate system during heat-treatment were investigated. The initial binder solutions were prepared by dissolving Al(OH)3 and Cr2O3 in aqueous H3PO4 solution. The binder solutions consolidated at 100°C. The as-consolidated products were heated at different temperature. The experimental results showed the phase evolution of the consolidated products as: amorphous phase in 300~800°C, Cr(PO3)3 and Cr4(P2O7)3 in 900~1200°C for chromium phosphate system binder; amorphous phase in 300~1000°C, Cr(PO3)3 and AlPO4 in 1100°C, Cr4(P2O7)3 and AlPO4 in 1200°C for aluminumchromium- phosphate system binder. The addition of chromium oxide demonstrates to strengthen amorphous network, which further improves the thermal stability.

Preparation and Properties of the Organic-Inorganic Composite Coating on Aluminum Alloy

2011 ◽  
Vol 675-677 ◽  
pp. 1197-1200
Author(s):  
Guo Jun Li ◽  
Xue Jun Cui ◽  
Rui Ming Ren
Keyword(s):  
Aluminum Alloy ◽  
Composite Coating ◽  
Lamellar Structure ◽  
Impact Resistance ◽  
Weight Ratio ◽  
Silica Sol ◽  
Nano Tio2 ◽  
Optimum Range ◽  
Acid Catalyzed ◽  
Inorganic Composite

The organic-inorganic hybrid sol was prepared using an alkaline silica sol modified by acid-catalyzed hydrolytic polycondensation of methyltrimethoxysilane (MTMS) in a water-bath condition of 60oC, and then the water-based primer and topcoat were prepared through adding the pigments and nano-TiO2 suspension respectively. Through spraying and baking, the organicinorganic composite coating on the treated aluminum alloy was obtained. The optimum range of P/B (weight ratio of the pigment/binder) is determined between 1:1 and 1.5:1 by investigating the influence of the P/B of the primer on the adhesion and impact resistance of the coating. The microstructure of the coating was characterized by optical microscopy and scanning electron microscopy. The results show that there are lots of holes and lamellar structure in the primer coating and the obtained topcoat coating is uniform, smooth and dense. The coating of ~30 μm in thickness is mainly composed of three elements of silicon, aluminum and titanium, in which transition layer of ~10 μm is included. The physicochemical properties suggest that the coatings on aluminum alloy can meet the needs of finishing coating very well.

Temperature-Driven Oxidation Behavior of Pure Iron Surface Investigated by Time-Resolved EXAFS Measurements

1998 ◽  
Vol 524 ◽  
Author(s):  
S. J. Doh ◽  
J. M. Lee ◽  
D. Y. Noh ◽  
J. H. Je
Keyword(s):  
Heat Treatment ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Rapid Heating ◽  
Oxidation Mechanism ◽  
Front Surface ◽  
Time Resolved ◽  
Treatment Conditions ◽  
Surface Front ◽  
Prolonged Heat

ABSTRACTThe surface-front oxidation mechanism of iron was investigated by time-resolved, glancingangle Fe K-edge fluorescence EXAFS measurements at various oxidation temperatures of 200-700 C. The glancing angle was chosen according to the depth of the oxide layer, roughly 1500-2000A. The oxidation behavior under rapid heating(up to 600°C within 10 minutes) was compared with the slowly heated oxidation process using the Quick-EXAFS measurements. In the slowly heated process, Fe3O4 was the dominating phase at a relatively low temperature (300-400 C) initially. However, at a relatively high temperature (above 600°C), the Fe2O3 and FeO crystalline phases are gradually enriched as the successive oxidation process involving intrusive oxygen proceeded. Remarkably under a prolonged heat treatment above 600°C, the stable FeO phase that exists in a deep-lying interface structure and Fe2O3 phase eventually dominates the thick front-surface structure. In a quickly heated process, however, Fe3O4 phase is less dominating, which is contradictory to the commonly accepted oxidation models. The EXAFS results are discussed in conjunction with the x-ray diffraction features under the same heat treatment conditions.

scholarly journals Arc Thermal Spray NiCr20 Alloy Coating: Fabrication, Sealant, Heat Treatment, Wear, and Corrosion Resistances

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Van Tuan Nguyen ◽  
Quy Le Thu ◽  
Tuan Anh Nguyen ◽  
Quoc Cuong Ly ◽  
Ly Pham Thi ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
Corrosion Resistance ◽  
Phase Composition ◽  
Corrosion Test ◽  
Annealing Temperature ◽  
Alloy Coating ◽  
Aluminum Phosphate ◽  
Annealing Temperatures ◽  
Wear And Corrosion

This study presents the effect of heat treatment on porosity, phase composition, microhardness, and wear and corrosion resistances of the thermal sprayed NiCr20 coating after sealing with aluminum phosphate. The annealing temperatures were varied in a range of 400 to 1000°C. The obtained results indicated the porosity of coating decreased with increasing the annealing temperature. After treatment at temperatures in range of 800-1000°C, more than 90% of initial pores in the coating were successfully filled with the sealants. The XRD data revealed not only the formation of new phases of other compounds, but also the interaction between coating and sealant. After heat treatment, wear resistance of coating was 12 times higher than that without heat treatment. The corrosion test in H2SO4 solution indicated that the presence of sealant in coatings increased their corrosion resistance. From these findings, application of these NiCr20 coatings to protect steel against wear and corrosion appears very promising.

Long-term stability of ICPCVD a-Si under prolonged heat treatment

2014 ◽  
Author(s):  
Kirsten L. Brookshire ◽  
Mariusz Martyniuk ◽  
K. K. M. B. Dilusha Silva ◽  
Yinong Liu ◽  
Lorenzo Faraone
Keyword(s):  
Heat Treatment ◽  
Term Stability ◽  
Long Term Stability ◽  
Prolonged Heat ◽  
Prolonged Heat Treatment

Characterization and corrosion behavior of electroless Ni-Mo-P/Ni-P composite coating in CO2/H2S/Cl− brine: Effects of Mo addition and heat treatment

2020 ◽  
Vol 403 ◽  
pp. 126416
Author(s):  
Jiankuan Li ◽  
Chong Sun ◽  
Morteza Roostaei ◽  
Mahdi Mahmoudi ◽  
Vahidoddin Fattahpour ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Composite Coating ◽  
Corrosion Behavior ◽  
Electroless Ni

Influence of SiC Content and Heat Treatment on the Corrosion Resis-Tance and Oxidation Resistance of Ni-P-SiC Composite Coating

2015 ◽  
Vol 817 ◽  
pp. 479-483
Author(s):  
Pan Li ◽  
Wan Chang Sun ◽  
Jun Gao ◽  
Quan Zhou ◽  
Pei Zhang
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Composite Coating ◽  
Oxidation Resistance ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
Treatment Temperature ◽  
Micro Hardness ◽  
Resis Tance ◽  
P Matrix

Ni-P alloy and SiC micron particles were codeposited on Q235 steel by electroless plating. The composition, microstructure, micro-hardness, corrosion resistance and oxidation resistance of the composite coating were studied. The results revealed that the deposited composite coating shows dispersed SiC particles and continuous Ni-P matrix. When the content of SiC was 8g/L and the heat treatment temperature was 300°C, the corrosion potential and corrosion current of Ni-P-SiC coating were-0.292V, and 8.2×10-7 A/cm2, respectively, while those of Ni-P composite coating were-0.501V, and 4.2×10-5 A/cm2, respectively. Ni-P-SiC composite coating with high content of SiC exhibits better oxidation resistance than Ni-P coating.

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