scholarly journals Corrosive effects of nitrate-containing phase change materials used with copper

2016 ◽  
Vol 9 (2) ◽  
pp. 75-83 ◽  
Author(s):  
Vladimír Danielik ◽  
Peter Šoška ◽  
Katarína Felgerová
Keyword(s):  
Corrosion Rate ◽  
Phase Change ◽  
Phase Change Materials ◽  
Corrosion Behaviour ◽  
Calcium Nitrate ◽  
Magnesium Nitrate ◽  
Nitrate Hexahydrate ◽  
Calcium Nitrate Tetrahydrate ◽  
Magnesium Nitrate Hexahydrate ◽  
Nitrate Tetrahydrate

Abstract The paper presents the results of a study on the corrosion behaviour of copper (EN CW004A) in five possible phase change materials (PCMs): magnesium nitrate hexahydrate pure and with an addition of Mg(OH)2 (0.5 wt. %) or Sr(OH)2 (0.5 wt. %) at 90 °C, calcium nitrate tetrahydrate at 50 °C and a mixture of magnesium nitrate hexahydrate and calcium nitrate tetrahydrate (1:1 mass ratio) at 72 °C. The corrosion rate of copper samples is low except for the use of Mg(NO3)2 · 6H2O with/without an addition of Mg(OH)2. The lowest corrosion rate was observed for the mixture Mg(NO3)2 · 6H2O—Ca(NO3)2 · 4H2O (1:1), and it was ca six times lower than that of pure magnesium nitrate hexahydrate.

scholarly journals SEM, EDS, and XPS Characterization of Coatings Obtained on Titanium During AC Plasma Electrolytic Process Enriched in Magnesium

2018 ◽  
Vol 18 (3) ◽  
pp. 68-78 ◽  
Author(s):  
K. Rokosz ◽  
T. Hryniewicz ◽  
S. Raaen ◽  
D. Matýsek ◽  
Ł. Dudek ◽  
...  
Keyword(s):  
Calcium Nitrate ◽  
Zinc Nitrate ◽  
Magnesium Nitrate ◽  
Nitrate Hexahydrate ◽  
Calcium Nitrate Tetrahydrate ◽  
Porous Coatings ◽  
Magnesium Nitrate Hexahydrate ◽  
Xps Characterization ◽  
Micro Arc Oxidation ◽  
Plasma Electrolytic

AbstractPlasma Electrolytic Oxidation (PEO) known also as Micro Arc Oxidation (MAO) process is widely used to fabricate porous coatings on titanium and its alloys mainly in water- and acid-based solutions to different applications, e.g. in biomaterials, catalysts, and sensors. In the present paper, the SEM, EDS, and XPS results of porous coatings obtained by PEO treatment on titanium in electrolytes based on concentrated phosphoric H3PO4 acid with calcium nitrate tetrahydrate Ca(NO3)2·4H2O, or magnesium nitrate hexahydrate Mg(NO3)2·6H2O, or zinc nitrate hexahydrate Zn(NO3)2·6H2O for 3 minutes at 200 Vpp (peak to peak) with frequency of 50 Hz, are presented. Based on EDS results, the Ca/P, Mg/P, and Zn/P ratios, which equal to 0.95, 0.176, and 0.231, respectively, were found out. The XPS studies of the top 10 nm of the porous layer clearly indicate that it contains mainly phosphates (PO43− and/or HPO42− and/or H2PO4−, and/or P2O74−) with titanium (Ti4+) and calcium (Ca2+) or magnesium (Mg2+), or zinc (Zn2+).

Densities of nitrate hydrates used as phase change materials

2017 ◽  
Vol 10 (2) ◽  
pp. 79-83
Author(s):  
Vladimír Danielik ◽  
Dominika Szendreiová
Keyword(s):  
Phase Change Materials ◽  
Liquid Mixtures ◽  
Liquid System ◽  
Zinc Nitrate ◽  
Magnesium Nitrate ◽  
Zinc Nitrate Hexahydrate ◽  
Nitrate Hexahydrate ◽  
Temperature Dependency ◽  
Magnesium Nitrate Hexahydrate ◽  
Different Temperatures

AbstractTemperature dependency of densities of the liquid system magnesium nitrate hexahydrate - zinc nitrate hexahydrate was measured. Densities of liquid mixtures were experimentally measured at different temperatures by a method using submersible corpuscle. Based on the obtained data, temperature dependence on the density was obtained. A model describing the density in the whole concentration range very well was created.

Temperature and concentration dependence of fluidity of mixed hydrated melts of calcium- and nickel(II)-nitrates

1979 ◽  
Vol 57 (15) ◽  
pp. 2028-2031 ◽  
Author(s):  
Nurul Islam ◽  
Anwar Ali
Keyword(s):  
Concentration Dependence ◽  
Linear Dependence ◽  
Calcium Nitrate ◽  
Configurational Entropy ◽  
Nitrate Hexahydrate ◽  
Calcium Nitrate Tetrahydrate ◽  
Intrinsic Volume ◽  
Nitrate Tetrahydrate ◽  
Arrhenius Temperature Dependence

The non-Arrhenius temperature dependence of fluidity, [Formula: see text], of molten mixtures of calcium nitrate tetrahydrate and nickel(II) nitrate hexahydrate has been explained in terms of equations based upon the Vogel–Tammann–Fulcher (VTF) and the configurational entropy (CEM) models. The role of the relevant parameters in understanding the successive variations in their behaviour with concentration has been examined. The concentration dependence of fluidity has been explained satisfactorily by an isoenergetic equation. In addition to the linear dependence of the pre-exponential terms of the VTF and the Doolittle equations on the ideal glass-transition temperature, T0, and the molar intrinsic volume, V0, respectively, linear interdependence of the two thermodynamic parameters, T0 on V0, has been found. Linear dependence of the corrected activation energy, Ecor, on the V0 and the T0 values have been demonstrated in the system under investigation.

scholarly journals Gradual Replacement of Ca2+ with Mg2+ Ions in Brushite for the Production of Ca1−xMgxHPO4·nH2O Materials

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 284
Author(s):  
Mazen Alshaaer ◽  
Khalil Issa ◽  
Abdulaziz Alanazi ◽  
Saida Abu Mallouh ◽  
Ahmed S. Afify ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Calcium Nitrate ◽  
Ammonium Hydroxide ◽  
Magnesium Nitrate ◽  
Molar Ratio ◽  
Partial Replacement ◽  
Nitrate Hexahydrate ◽  
Calcium Nitrate Tetrahydrate ◽  
X Ray ◽  
Starting Solution

The present study investigates the gradual replacement of Ca2+ with Mg2+ ions in brushite (CaHPO4·2H2O). To date, this approach has not been systematically explored and may prove beneficial for the production of Ca1−xMgxHPO4·nH2O materials with tailored properties which are suitable for environmental and medical applications. For their production, solutions of sodium dihydrogen orthophosphate dehydrate, NaH2PO4·2H2O, calcium nitrate tetrahydrate, Ca(NO3)2·4H2O, magnesium nitrate hexahydrate, Mg(NO3)2·6H2O and ammonium hydroxide solution, NH4OH, were used. At low Mg/Ca molar ratios (up to 0.25) in the starting solution, partial replacement of Ca with Mg takes place (Mg doping) but no struvite is produced as discrete phase. When the Mg/Ca molar ratio increases gradually to 1.5, in addition to Mg-doped brushite, struvite, NH4MgPO4·6H2O, precipitates. The microstructure of the materials produced for different degrees of Ca replacement with Mg has been analyzed in depth with the use of powdered XRD (X-ray diffraction), XPS (X-ray photoelectron spectroscopy), thermogravimetric (TG) analysis and SEM (scanning electron microscopy). The results of this study prove that the Mg/Ca ratio in the starting solution can be monitored in such a way that materials with tailored composition are obtained.

scholarly journals Experimental Research of the Heat Storage Performance of a Magnesium Nitrate Hexahydrate-Based Phase Change Material for Building Heating

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7108
Author(s):  
Yang Li ◽  
Caixia Wang ◽  
Jun Zong ◽  
Jien Ma ◽  
Youtong Fang
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Heat Storage ◽  
Thermal Storage ◽  
Magnesium Nitrate ◽  
Storage Device ◽  
Outer Side ◽  
Nitrate Hexahydrate ◽  
Magnesium Nitrate Hexahydrate ◽  
Change Material

Phase change heat storage material is a preferred material in solar building heating or off-peak electric-heat storage heating technology and is the research focus. A compact phase change thermal storage device has been designed and experimentally studied for improving heating system load in this work. A new type, magnesium nitrate hexahydrate-based phase change material has been studied to improve the cooling degree and crystallization difficulty. The focus of this study is on the heat charging and discharging characteristics of this new phase change material. The heat storage device has two groups of coils, the inner side which carries water and the outer side which is the phase change material. A testing system was built up to value the thermal cycling performance of the heat storage device. The measurement data include phase change material temperature field, water inlet and water outlet mean temperature, heat charging and heat discharging depth, and flow rates over the operating period. The results show the phase change material has a quick response with the operating temperature range of 20–99 °C. Its latent heat is 151.3 J/g at 91.8 °C. The heat storage density of this phase change material is about 420 MJ/m3. The thermal performance degradation is about 1.8% after 800 operation cycles. The phase change thermal storage device shows flexibility and a great potential to improve the capacity and economy of heating systems.

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