Novel hydroxyapatite-based consolidant and the acceleration of hydrolysis of silicate-based consolidants

2014 ◽  
Vol 1656 ◽  
pp. 9-14 ◽  
Author(s):  
Sonia Naidu ◽  
Chun Liu ◽  
George W. Scherer
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
Thermal Degradation ◽  
Calcium Chloride ◽  
Coupling Agent ◽  
Hydrogen Phosphate ◽  
Water Sorptivity ◽  
Indiana Limestone ◽  
Hydrolysis Of ◽  
Diammonium Hydrogen

ABSTRACTThis paper discusses the effectiveness of hydroxyapatite (HAP) as an inorganic consolidant for physically weathered Indiana Limestone, and as a coupling agent between limestone and a silicate consolidant. A double application is investigated, in which samples are coated with HAP followed by a commercially available silicate-based consolidant (Conservare® OH-100). To artificially weather limestone, a thermal degradation technique was utilized. Diammonium hydrogen phosphate (DAP) salt was reacted with limestone, alone and with cationic precursors, to produce HAP films. The dynamic elastic modulus, water sorptivity and tensile strength of the treated stones were evaluated. HAP was found to be an effective consolidant for weathered Indiana Limestone, and its performance was enhanced by addition of millimolar quantities of calcium chloride. However, HAP was not useful as a coupling agent; a double treatment with DAP is more effective than sequential treatment with DAP and Conservare®.

Facile Synthesis of Hydroxyapatite Nanorods with Controlled Sizes and Morphologies

2010 ◽  
Vol 148-149 ◽  
pp. 1584-1587
Author(s):  
Sha Sha Lv ◽  
Ning Wang ◽  
Gui Cun Li ◽  
Hong Rui Peng
Keyword(s):  
Hydrothermal Method ◽  
Calcium Chloride ◽  
Hydrogen Phosphate ◽  
Facile Synthesis ◽  
High Quality ◽  
Facile Hydrothermal Method ◽  
Diammonium Hydrogen Phosphate ◽  
Diammonium Hydrogen

High quality hydroxyapatite (HAP) nanorods have been synthesized at 180 °C by a facile hydrothermal method using calcium chloride and diammonium hydrogen phosphate as precursors in the absence of any surfactants. The diameters and lengths of HAP nanorods are in the range of 40-80 nm and 0.2-2.0 μm respectively. The sizes and morphologies of HAP nanorods can be controlled by adjusting the synthetic parameters, such as reaction temperatures, and types of surfactants. A possible mechanism was also proposed to explain the growth of the HAP nanorods.

Preliminary Results of the Use of Hydroxyapatite as a Consolidant for Carbonate Stones

2011 ◽  
Vol 1319 ◽  
Author(s):  
Enrico Sassoni ◽  
Sonia Naidu ◽  
George W. Scherer
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
Dynamic Elastic Modulus ◽  
Capillary Absorption ◽  
Treatment Technique ◽  
Constant Weight ◽  
Lattice Match ◽  
Partial Immersion ◽  
Phase Characterization ◽  
Indiana Limestone

ABSTRACTThe effectiveness of using hydroxyapatite (HAP) as a consolidant for carbonate stones was evaluated. HAP was chosen as a consolidating agent since it is notably less soluble than calcite and has a similar crystal structure and a close lattice match to it. Among possible methods for forming HAP, the reaction between the calcite of the stone and a solution of diammonium hydrogen phosphate (DAP) in mild conditions was chosen. Indiana Limestone samples, artificially damaged by heating to 300°C for 1 hour, were treated with a 1 molar DAP solution by partial immersion and capillary absorption for 48 hours or by brushing until apparent refusal and wrapping with a plastic film for 48 hours. After washing in deionized water for 3 days and drying under a fan at room temperature until constant weight, the improvements in dynamic elastic modulus and tensile strength were evaluated. The formation of calcium phosphate phases was observed by scanning electron microscopy (SEM) and the phase characterization performed by energy dispersive X-ray spectroscopy (EDS) and electron back-scattered diffraction (EBSD). The water absorption modification after the consolidating treatment was then assessed. Results show that treated samples experienced significant increases in dynamic elastic modulus and tensile strength, as a consequence of crack reduction and pore filling consequent to HAP deposition at grain boundaries. The sorptivity of the treated samples is reduced by 26-44% (based on treatment technique), so that water and water vapor exchanges with the environment are not blocked.

Sintering Behavior and Diametral Tensile Strength Properties of Hydroxyapatite-Zirconia Composites

2015 ◽  
Vol 827 ◽  
pp. 87-90 ◽  
Author(s):  
Eko Pujiyanto ◽  
Pringgo Widyo Laksono ◽  
Sagiran
Keyword(s):  
Tensile Strength ◽  
Strength Properties ◽  
Molar Ratio ◽  
Sintering Behavior ◽  
Strength Testing ◽  
Hydrogen Phosphate ◽  
Precipitation Treatment ◽  
Diametral Tensile Strength ◽  
Diammonium Hydrogen

. The aim of this study is to evaluate the sintering behavior and diametral tensile strength properties of hydroxyapatite-zirconia (HA-ZrO2) composites. HA powder were synthesized from gypsum waste with diammonium hydrogen phosphate (DHP) solution via microwave-precipitation treatment. HA mixed with various amounts of ZrO2 (0, 20, 30 and 40 wt.%) for six hours. HA-ZrO2 powder were molded in a metal die and pressed at 100 MPa. The green bodies were sintered for 2 hours at temperature 1450°C. Characterization of HA and HA-ZrO2 composites were conducted by XRD, XRF and SEM-EDX. The apparent porosity of HA-ZrO2 composites were measured using the Archimedes method. Diametral tensile strength testing of HA-ZrO2 composites were loaded at a crosshead speed of 5 mm/min. The results of the characterization of HA powder are the main (h k l) indices for HA are: (2 1 1), (2 0 2) and (0 0 2), Ca/P molar ratio is 1.71, level of purity is 88.68 %. The main (h k l) indices for HA-ZrO2 composites are: (2 2 0), (0 2 10) and (2 0 20). Porosity of HA-ZrO2 composites values in the range of 39.59-19.82%. Diametral tensile strength of HA-ZrO2 composites increased from 4.96 to 7.77 MPa when amounts of ZrO2 increased up to 40 wt%. This phenomenon is caused by porosity decrease and crack deflection.

scholarly journals Three-dimensional thermomechanical converting of CTMP substrates: effect of bio-based strengthening agents and new mineral filling concept

Cellulose ◽  
2021 ◽  
Vol 28 (15) ◽  
pp. 9751-9768
Author(s):  
Teija Laukala ◽  
Sami-Seppo Ovaska ◽  
Ninja Kerttula ◽  
Kaj Backfolk
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
Three Dimensional ◽  
Microfibrillated Cellulose ◽  
New Mineral ◽  
Thermomechanical Pulp ◽  
Cationic Starch ◽  
Precipitated Calcium Carbonate ◽  
Filling Method ◽  
Positive Effect

AbstractThe effects of bio-based strengthening agents and mineral filling procedure on the 3D elongation of chemi-thermomechanical pulp (CTMP) handsheets with and without mineral (PCC) filling have been investigated. The 3D elongation was measured using a press-forming machine equipped with a special converting tool. The strength of the handsheets was altered using either cationic starch or microfibrillated cellulose. Precipitated calcium carbonate (PCC) was added to the furnish either as a slurry or by precipitation of nano-sized PCC onto and into the CTMP fibre. The 3D elongation of unfilled sheets was increased by the dry-strengthening agents, but no evidence on the theorised positive effect of mineral fill on 3D elongation was seen in either filling method. The performance of the strengthening agent depended on whether the PCC was as slurry or as a precipitated PCC-CTMP. The starch was more effective with PCC-CTMP than when the PCC was added directly as a slurry to the furnish, whereas the opposite was observed with microfibrillated cellulose. The 3D elongation correlated positively with the tensile strength, bursting strength, tensile stiffness, elastic modulus and bending stiffness, even when the sheet composition was varied, but neither the strengthening agent nor the method of PCC addition affected the 3D elongation beyond what was expectable based on the tensile strength of the sheets. Finally, mechanisms affecting the properties that correlated with the 3D elongation are discussed.

scholarly journals Clay-Based Products Sustainable Development: Some Applications

2021 ◽  
Vol 13 (3) ◽  
pp. 1364
Author(s):  
Michele La Noce ◽  
Alessandro Lo Faro ◽  
Gaetano Sciuto
Keyword(s):  
Sustainable Development ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Basalt Fibers ◽  
Future Studies ◽  
Clay Bricks ◽  
Brick Powder ◽  
Alkaline Resistance ◽  
Raw Earth

Clay has a low environmental impact and can develop into many different products. The research presents two different case studies. In the first, the clay is the binder of raw earth doughs in order to produce clay-bricks. We investigate the effects of natural fibrous reinforcements (rice straws and basalt fibers) in four different mixtures. From the comparison with a mix without reinforcements, it is possible to affirm that the 0.40% of basalt fibers reduce the shrinkage by about 25% and increase the compressive strength by about 30%. Future studies will focus on identifying the fibrous effects on tensile strength and elastic modulus, as well as the optimal percentage of fibers. In the second study, the clay, in form of brick powder (“cocciopesto”), gives high alkaline resistance and breathability performance, as well as rendering and color to the plaster. The latter does not have artificial additives. The plaster respects the cultural instance of the original building. The research underlines how the use of a local (and traditional) material such as clay can be a promoter of sustainability in the contemporary building sector. Future studies must investigate further possible uses of clay as well as a proper regulatory framework.

scholarly journals Influence of Alumina Nanofibers Sintered by the Spark Plasma Method on Nickel Mechanical Properties

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 548 ◽  
Author(s):  
Leonid Agureev ◽  
Valeriy Kostikov ◽  
Zhanna Eremeeva ◽  
Svetlana Savushkina ◽  
Boris Ivanov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Strength Properties ◽  
Alumina Nanoparticles ◽  
Metal Powders ◽  
Wide Range ◽  
The Matrix ◽  
Spark Plasma ◽  
Average Size

The article presents the study of alumina nanoparticles’ (nanofibers) concentration effect on the strength properties of pure nickel. The samples were obtained by spark plasma sintering of previously mechanically activated metal powders. The dependence of the grain size and the relative density of compacts on the number of nanofibers was investigated. It was found that with an increase in the concentration of nanofibers, the average size of the matrix particles decreased. The effects of the nanoparticle concentration (0.01–0.1 wt.%) on the elastic modulus and tensile strength were determined for materials at 25 °C, 400 °C, and 750 °C. It was shown that with an increase in the concentration of nanofibers, a 10–40% increase in the elastic modulus and ultimate tensile strength occurred. A comparison of the mechanical properties of nickel in a wide range of temperatures, obtained in this work with materials made by various technologies, is carried out. A description of nanofibers’ mechanisms of influence on the structure and mechanical properties of nickel is given. The possible impact of impurity phases on the properties of nickel is estimated. The tendency of changes in the mechanical properties of nickel, depending on the concentration of nanofibers, is shown.

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