Weight Loss Rate Of Samples Research Articles

The effect of calcium phosphate and silk fibroin nanofiber tuning on properties of calcium sulfate bone cements

Calcium sulfate (CS) bone cements have been used as bone substitutes for a long time, but their clinical use is currently limited due to their rapid degradation rate and brittleness. This work aimed to study the effect of α-tricalcium phosphate (α-TCP) and silk fibroin nanofibers (SFF) on CS bone cements. The bone cements were prepared from α-CS hemihydrate (α-CSH), calcium sulfate dihydrate (CSD; as a setting accelerator) and varying α-TCP contents (0%, 5%, 10%, 15%, 20% and 25%), with SFF solution or deionized water as the solidification solution at the same liquid/solid ratio. Scanning electron microscopy, particle size distribution, x-ray diffraction and Fourier transform infrared spectroscopy were used to measure the composition and characterize the properties of the materials. The compressive strength, setting time and weight loss rate of samples were also tested. Cytotoxicity was evaluated by a Cell Counting Kit-8 assay. The results suggest that the tuning of α-TCP and SFF has an important role in determining the compressive strength and degradation rate of CS bone cements, and the properties could be changed by varying the content of α-TCP. Moreover, cell experiments showed no toxicity of the samples towards MC3T3 cells. Thus, the materials prepared from α-CSH, CSD, α-TCP and SFF in this work could provide the basis for research into CS-based bone repair materials.

The effect of ARB process on corrosion behavior of nanostructured aluminum alloys in Na2HPO4·12H2O and Zn(NO3)2·6H2O PCMs

Phase change materials (PCMs), have high thermal energy storage due to hidden heat. One of the PCMs is hydrate salts. The insufficient long term stability of the storage materials, as containers, are the main concern in the energy storage systems which were investigated in this study. In this order, various common metals (Fine-grained Al1100 and Al6061 alloys by six cycles of accumulative roll bonding (ARB)) process were selected, and their corrosion resistance in contact with two different hydrate salts of (Na2HPO4·12H2O and Zn(NO3)2·6H2O) were tested. The immersion test method was utilized. In this way, samples were placed in the test tubes containing molten hydrate salts into a thermo-static water bath in three different periods of six, twelve and eighteen days at the temperature range of 55 to 60 °C. After each period, the sample weight loss rate was measured, and then the corrosion rate was calculated. The corrosion rate of ARBed Al 1100 and ARBed Al 6061 alloys in the Na2HPO4·12H2O at the end of eighteen days were 103.07 and 78.82 mpy, respectively. Furthermore, the corrosion rate of ARBed Al 1100 and ARBed Al6061 alloys in the Zn(NO3)2·6H2O was reported 88.67 and 68.71 mpy, respectively. The results indicated that the corrosion rate for Al1100 alloy is less and more than Al6061 alloy in the molten Na2HPO4·12H2O and molten AZn(NO3) 2·6H2O, respectively.

Study on reduction mechanism of Fe2O3 by NH3 under SNCR condition

Amino compounds were injected into a boiler at high-temperature area usually to realized De-NOx. However, amino compounds were highly corrosive. The metal tube skin of stage III superheater in a medium temperature separation circulating fluidized bed boiler (MTS-CFBB) was investigated to verify the corrosion effect of amino compounds on the boiler tube wall. The sodium salt which was found in the inner layer of the metal tube skin indicated that large area cracking occurred at the metal tube during the operation process; and further indicated that the corrosion rate of the tube wall was speedy. Meanwhile, the tube furnace experimental system and the reaction equations module in HSC Chemistry 6.0 were used to obtain the reduction properties of NH3 on Fe2O3 at high temperature. The weight loss rate of Fe2O3 under N2-NH3 atmosphere increased from 3.3 wt% to 5.5 wt%, when the temperature rose from 600 °C to 900 °C, and the weight loss rate of samples did not increase any more with the temperature rising to 1000 °C. The injected NH3 reduced the Fe3O4 to form FeO quickly at 810 °C. With the thermal stress caused by the boiler load adjustment and start up or shut down, the looser FeO formed at the interior of tubes, and then, the different expansion coefficient of Fe based compounds led to the extensive cracking. In summary, NH3 generated by SNCR was the main reason for corrosion happened on the tubes at high-temperature.

Oxidation mechanism of SiC–Zirconia–Glass ceramic coated carbon/carbon composites at 1123–1273 K

A novel type of SiC–Zirconia–Glass coating for carbon/carbon(C/C) composites was designed and prepared by slurry method and their microstructure and oxidation behavior at temperatures of 1123–1273K were investigated. The results show that the weight loss rate of samples was below 1.5% after oxidation of 70h and have excellent mechanical properties remaining after a 1123–1273K oxidation process. The relationship between the weight loss rate and oxidation time can be fitted to an exponential curve and the reaction activation energy of diffusion through the coating cracks was 16.68kJmol−1. It was found that the oxidation model of SiC–ZrO2–Glass coated C/C composites was not exactly follow to Arrhenius's law during temperature of 1123–1273K and has characteristics of defective oxidation.

Co-Combustion of Paper Mill Sludge and Bituminous Coal in Air Using Thermogravimetric Analyzer

The combustion of paper mill sludge and bituminous coal in air was analyzed using a thermogravimetric instrument. TG and DTG curves for the blends lies between that of the individual fuels, and the main combustion characteristics of blends depended on individual fuels and followed the weighted average. As the blending ratio of paper mill sludge was increased from 10% to 90%, the ignite temperature (Ti) decreased from 529.6°C. to 275.6°C., and residual weight increased from 19.28% to 47.39%. The TG profiles of sample were almost the same at different heating rates, however there was a big difference between the DTG profiles. The maximum weight loss rate of sample increased obviously with the increment of heating rate. This work contributes to the comprehensive understanding of paper mill sludge and bituminous coal combustion and development of co-combustion technology.

A study on municipal solid waste (MSW) combustion in N2/O2 and CO2/O2 atmosphere from the perspective of TGA

Abstract In this paper, the combustion behavior of municipal solid waste (MSW) is carried out in a thermogravimetric analyzer under different N 2 /O 2 and CO 2 /O 2 atmospheres with temperature ranging from 100 °C to 1000 °C. TG (thermogravimetric) and DTG (derivative thermogravimetric) curves are analyzed. The n th order reaction fitting model is used to yield the activation energy of reduction process according to the degree of conversion. The results indicate that all samples lose most their weight between 200 °C and 540 °C. As the oxygen concentration increased, conversion rate curves and DTG curves shift to lower temperature without significant change in its shape. At the same oxygen concentration, the peak values in CO 2 /O 2 atmosphere are smaller than those in N 2 /O 2 atmosphere, indicating that CO 2 has a higher inhibitory effect than N 2 on MSW combustion. After 600 °C, the weight loss peak appears much later in CO 2 /O 2 atmosphere than it does in N 2 /O 2 atmosphere. With the increase of heating rate, the maximum weight loss rates of samples increase obviously. The three-step reaction of n th order reaction model fits the weight loss very well.

Co-combustion kinetics of sewage sludge with coal and coal gangue under different atmospheres

In this paper, the co-combustion behaviour of sewage sludge with coal gangue and coal were investigated by a thermogravimetric analysis (TGA) in the temperature range from ambient temperature to 1000 °C. Experiments were carried out with about 10 mg of sample in five different atmospheres: 20% oxygen in nitrogen, 30% oxygen in nitrogen, 40% oxygen in nitrogen, 60% oxygen in nitrogen and 70% oxygen in nitrogen, thermogravimetry (TG) and DTG curves were analyzed. A method of direct non-linear regression of the kinetic equation was used to a simultaneous calculation of the kinetic parameters (the apparent activation energy, the reaction order and the frequency factor) from a single TG curve in various atmospheres. The results indicate that: with the increase of heating rate the maximum weight loss rate of samples increase obviously. The activation energy values range from 51.2 kJ mol −1 to 164.4 kJ mol −1.

Isoconversional kinetic analysis of co-combustion of sewage sludge with straw and coal

In this paper, the co-combustion behaviour of sewage sludge with straw and coal were carried out in a thermogravimetric analyzer under different atmospheres and at different heating rates (10, 20 and 40 K min −1) in the temperature range from ambient temperature to 1000 °C. TG and DTG curves were analysed. The Flynn–Wall–Ozawa’s (FWO) and Kissinger–Akahira–Sunose’s (KAS) isoconversional methods were used to yield dependency of the activation energy of reduction process on the degree of conversion. The values of E α were obtained. The results indicate that: with the increase of heating rate, the maximum weight loss rate of samples increase obviously. The activation energy is practically constant in the 0.2 ⩽ α ⩽ 0.9 range, with the average values of E α = 137.27 and 132.38 kJ mol −1 calculated by FWO and KAS methods, respectively.

Effects of the impact angle variations on the erosion rate of glass in powder blasting process

Sandblasting, a conventional technique which is used for paint or scale removing, deburring, and glass decorating, has recently been developed into a powder blasting technique for brittle materials capable of producing micro-structures larger than 100 μm. This article describes an investigation of the effects of the impact angle of particles, the scanning times, and the standoff distance on the surface roughness, the weight-loss rate of samples with no mask, and the wall profile and over-etching of samples with different mask patterns in powder blasting of soda-lime glass. The parameters are the various impact angles between 50 and 90°, the scanning times of a nozzle up to 40, and the standoff distances between 70 and 100 mm. The widths of the mask pattern are 0.2 mm, 0.5 mm, and 1 mm. The powder used is Al2O3 sharp particles, WA#600. The mass flow rate of powder during the erosion test is constant at 175 g/min and the blasting pressure of the powder is 0.2 Mpa. After a series of necessary experiments are performed, the results are investigated and analysed. As a result, a fundamental basis is established that can be applied to powder blasting to produce micro-mechanical parts of glass.

Effect of magnetic field on the gas-jet boosted radio frequency glow discharge atomic emission spectrometry

The effect of a magnetic field on the radio frequency (rf) powered gas-jet boosted glow discharge (GD) source was investigated. The fundamental characteristic study includes the effects of discharge power of 10–50 W, and pressures range from 2 to 7 torr, on dc bias potential, sample weight loss rate and emission intensity with and without magnetic field. The bias potential and sample weight loss do not change with pressure above approximately 4 torr; however, as the pressure is dropped below approximately 4 torr there is a significant decrease in the bias potential and sample weight loss with addition of the magnetic field, while significant enhancement in signal intensity was observed with the addition of magnetic fields using Cu samples at 40 W, 200 ml/min gas flow rate and 5 torr pressure. The Cu(I) 324.7-nm and Cu(I) 327.4-nm wavelengths were enhanced as much as three times, while one order of magnitude enhancement was observed at the Cu(II) 224.7-nm wavelength. These results show that a magnetic field in this system only enhanced the excitation of sputtered atoms, and not on the sputtering. Both magnetic and non-magnetic boosted rf-GD shows a short-term precision of <1% RSD and long-term stability of <5% RSD for both major and trace element lines. Calibration curves are linear over 3–4 orders of magnitude with a general improvement of linearity by ratioing the signal to an internal standard of the matrix in both systems. Limits of detection for magnetic boosted GD are tens part per billion from many trace elements in low alloy steel which is an order of improvement over conventional rf-GD system.

Global kinetic constants for thermal oxidative degradation of a cellulosic paper

Values of global kinetic constants for pyrolysis, thermal oxidative degradation, and char oxidation of a cellulosic paper were determined by a derivative thermal gravimetric study. The study was conducted at heating rates of 0.5, 1, 1.5, 3, and 5°C/min in ambient atmospheres of nitrogen, 0.28%, 1.08%, 5.2% oxygen concentrations, and air. Sample weight loss rate, concentrations of CO, CO 2, and H 2O in the degradation products, and oxygen consumption were continuously measured during the experiment. Values of activation energy, pre-exponential factor, orders of reaction, and yields of CO, CO 2, H 2O, total hydrocarbons, and char for each degradation reaction were derived from the results. Heat of reaction for each reaction was determined by differential scanning calorimetry. A comparison of the calculated CO, CO 2, H 2O, total hydrocarbons, sample weight loss rate, and oxygen consumption was made with the measured results using the derived kinetic constants and accuracy of the values of kinetic constants was discussed.