首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
《文物保护研究》2013,58(1):23-29
Abstract

Upon aging, paper documents and books become progressively damaged. Paper deacidification is a fundamental conservation intervention. In this study, we report on the use of nanoparticles of titanium dioxide (TiO2) and magnesium hydroxide (Mg(OH)2) associated with hydroxyethylcellulose (HEC) to inhibit acidification, photo-induced degradation, and biodeterioration of paper. With the aid of ultrasound, Mg(OH)2 nanoparticles with a narrow size distribution can be obtained through homogeneous precipitation in water. Furthermore, to demonstrate the efficacy of the nanocomposite and the performance of treated and untreated paper, photo- and thermal-induced degradation is discussed. The results show that using the controlled double-jet precipitation (CDJP) it is possible to synthesize Mg(OH)2 particles with a narrow size distribution (18–87 nm). The nanocomposite of Mg(OH)2–TiO2–HEC increases the durability of paper by imparting fungal growth resistance (D = 34.6 mm), moderate alkalinity (pH = 8.4), mechanical reinforcement (from 817–896 N/m), and UV protection. Additionally, there is a slight color difference (ΔE* = 0.8) between the treated and untreated paper. Both photodegradation and thermal degradation indicate that the paper treated with this nanocomposite (Mg(OH)2–TiO2–HEC) has increased stability.  相似文献   

2.
A new coating system for archeological bronze protection that consists of a primer coating and a top coating was prepared in this study. The primer coating was prepared by mixing water-based acrylic emulsion with 1,2,3-benzotriazole, and the ultraviolet (UV) light-resistant top coating was prepared by mixing water-based acrylic emulsion with nano-sized TiO2 and SiO2 particles. UV light resistance and visible light transmission, contact angle, corrosion resistance, and mechanical properties of the new coating system were investigated and the results showed that UV resistance, hydrophobicity, oleophobicity, glossiness, and corrosion resistance all were improved. Application of the new system on real archaeological bronzes showed that the coating film was colorless, odorless, transparent, soft low-lustre, removable, and the original appearance of the archaeological bronze was well maintained.  相似文献   

3.
ABSTRACT

A decontamination treatment using liquid CO2 (li-CO2) and specifically developed for the requirements of museum objects (Lombardo, T., M. Wörle, V. Hubert, E. Hildbrand, I. Mayer, C. Hinterleitner, U. von Arx. 2020. “Influence of Process Parameters on Chlorinated Biocide Decontamination by li-CO2 on Artificially Contaminated Model Materials.” Studies in Conservation, in press, doi:10.1080/00393630.2019.1641001) was first tested on model materials of wood (with and without coating), silk, and wool with different dyes, paper, and leather in order to evaluate possible material changes. Then, selected museum objects from the collection of the Swiss National Museum were treated to determine the efficiency of biocide decontamination and any resulting chemical and/or structural changes. Results show that dichlorodiphenyltrichloroethane (DDT), pentachlorophenol (PCP), lindane, and chlorpyrifos were successfully removed. Wool, silk, leather, and non-coated wood did not experience any detectable modifications, while moderate to major modifications were observed in wood coated with shellac and polychromy.  相似文献   

4.
ABSTRACT

Previously, heavy use of biocides for the treatment of objects made of organic materials in museum collections (e.g. ethnographic, historical collections) was very common. Now suitable decontamination methods/technologies are being sought. A decontamination treatment by li-CO2 was optimized that considered the specific requirements of museum objects. The treatment was tested on model materials artificially contaminated with biocide solutions containing dichlorodiphenyltrichloroethane (DDT), pentachlorophenol (PCP), lindane, and permethrin or cypermethrin. High decontamination was achieved for DDT, lindane, PCP, and permethrin on artificially biocide loaded wool and wood model materials. Optimal process parameter settings for li-CO2 decontamination include a single 30?min cycle for woolen materials and three sequential 30?min cycles each for wood. These methods allow a reduction of at least 90% of all biocides for wool and between 70% and 85% for wood. Decontamination of the latter was more effective for less polar biocides as DDT and permethrin. Despite a significant improvement in decontamination for wood using co-solvents such as acetone, ethanol, and methyl tertiary-butyl ether (MTBE), their use is not recommended due to the increased risk of damage to the objects, in particular if a surface coating is present.  相似文献   

5.
《文物保护研究》2013,58(3):148-152
Abstract

Mineralogical changes which occur during the reaction of copper(II) chloride with carbonate in aqueous solution have been investigated, and compared with those involving copper(I) chloride, nantokite, CuCI, and copper artifacts coated with malachite, CU2CO3(OH)2 The reactions observed and the products obtained are seen to have implications with respect to the use of aqueous sodium carbonate solutions to stabilize archaeological copper objects. The frequent observation of the mineralogically rare species chalconatronite, Na2Cu(CO3)2·3H2O, on the surface of treated objects is readily explained by known reaction chemistry. Its formation can be minimized by washing the object after treatment.  相似文献   

6.
《文物保护研究》2013,58(3):134-142
Abstract

Naturally occurring pigments used by Aborigines in rock paintings have been collected in Western Australia. They area red pigment (mainly hematite, Fe2O3)(from a red ochre mine worked until historic times by Aborigines, and a white pigment (huntite, Mg3Ca(CO3)4) which is still collected and used by Aborigines. Samples were also taken from rock paintings in which these pigments were used or were thought to have been used. The pigment samples were analysed to establish chemical, mineralogical, and physical properties. The paint samples were examined microscopically and with an electron probe to study their relationship with the rock surface and with other paint layers. The relationship between the pigments’ properties and their durability is discussed.  相似文献   

7.
none 《文物保护研究》2013,58(4):253-266
Abstract

The use of sodium nitrite (NaNO2) as a corrosion inhibitor for wet archeological metal objects presents potential advantages of near neutral pH, low concentration, effectiveness on several metals, and compatibility with organic materials. The effectiveness of NaNO2 as a corrosion inhibitor for storage of chloride-containing marine archeological metal objects from the wreck of the USS Monitor was evaluated using marine-corroded carbon steel analogs. The samples were tested in varying concentrations of NaNO2 and evaluated visually and by monitoring solution chemistry using ion chromatography (IC). It was found that a concentration of 1000 ppm NaNO2, replaced four times, was effective at protecting corroded carbon steel in the presence of chlorides. Nitrite solutions were no more rapid than sodium hydroxide (NaOH) at extracting chlorides from marine steel at equal concentrations and were considerably slower than 2% NaOH. IC analyses indicated that NO2 does not easily oxidize to NO3 under normal conditions, but does so readily when a polarizing current is applied, making nitrites unsuitable for electrolytic reduction treatments. Sodium nitrite does show promise as a storage solution prior to desalination of marine metals or after desalination to prevent flash corrosion during rinsing baths.  相似文献   

8.
ABSTRACT

The surface texture of a stone represents a sensitive parameter in evaluating its conservation state. In monuments and sculptures, in fact, external agents continuously alter the appearance of stones, determining peculiar weathering patterns and modifying properties such as retention of water and particles, interaction with light, color, and finishing. The application of protective coatings also determines changes in surface appearance of a stone, usually evaluated and monitored by color change tests. Surface metrology methods offer the possibility to quantify these changes, evaluating the impact of external agents (natural, i.e. weathering, and artificially, i.e. protective coatings) on natural stones. In this research, we demonstrate the potential of surface areal measurements in describing the evolution of weathering processes and the effects of protective treatments on porous stone materials. The obtained results suggest that the extent of the modifications is related to the scale of observation (small- vs. large-scale undulations, i.e. roughness and waviness, respectively), with an overall increase of surface roughness as the weathering proceeds. Unexpectedly, coatings based on nanoparticle dispersions increase the topographic height parameters, due to the absence of a homogeneous film.  相似文献   

9.
《文物保护研究》2013,58(2):147-153
Abstract

The compound 5-amino-2-mercapto-1,3,4-thiadiazole (AMT) is utilized in the conservation of archaeological and artistic bronze artifacts, for their protection and for the removal of corrosion products. Many authors have discussed the utility and efficacy of this, but few have studied the products resulting from the reaction of AMT with bronze or with the corrosion products of bronze; this leaves the restorer with many doubts concerning the acceptability of this method. This paper discusses the study of products obtained from the reaction of AMT with synthesized corrosion products of bronze (malachite, paratacamite and brochantite) and with the commercial bronze alloy TM 23 (Cu 72%, Pb 15%, Zn 8% and Sn 5%). It was found that the film obtained from the direct reaction of AMT with the bronze alloy can be AMT itself, or the metallic complex Cu(C2H2N3S2)2·H2O if AMT is applied in a solution of an oxidizing acid. These results are expected to be of value to conservation scientists and restorers/ conservators concerned with the use of AMT for the conservation of bronze artifacts.  相似文献   

10.
《文物保护研究》2013,58(4):197-204
Abstract

This work combines our observation that the details of marble statues that have already been lost from the calcite surface are preserved in the gypsum layer, with our research on the mechanism of marble sulfation, to lead to a consolidation of the gypsum, transforming it back to calcium carbonate (calcite) using carbonate ions in solution. Our research shows the mechanism of the conversion of gypsum to calcite, the rate determining steps being the desorption and diffusion of CO2?3 We found that the reproduction of the surface detail and the improvement of the mechanical properties was very satisfactory.  相似文献   

11.
《文物保护研究》2013,58(4):227-236
Abstract

This article compares chemical dechlorination treatments (immersion in sodium hydroxide or alkaline sulphite) and electrochemical treatments of iron bars from the Gallo-Roman period excavated from a marine environment. Some important parameters, such as storage before treatment, temperature, solution composition, and drying after treatment, were varied during the study to assess their influence on the chloride extraction process. The kinetics of these treatments depend mainly on chloride diffusion through the corrosion layers. The kinetics are promoted by high temperatures and, in the case of electrolysis, by the electric field effect. The reduction of corrosion products during electrolysis occurs only for objects previously stored in air. In fact, the manner in which the objects are stored before treatment is critical in the dechlorination processes. The sooner the objects are treated after excavation (with water storage), the better the removal of chloride ions, in both chemical immersion and electrolysis treatments. But if the object is stored in air, material losses occur, and only electrolysis results in complete extraction of the chlorides. These differences are due to modifications in the corrosion products during storage. Drying after treatment also has a significant impact on the composition of the corrosion layers. If the objects are dried too quickly, Fe(OH)2 oxidizes into FeOOH, which thus forms a layer with low cohesion.  相似文献   

12.
《文物保护研究》2013,58(4):264-272
Abstract

The removal of calcareous accretions from archaeological bronzes can be a difficult step in their conservation. Chemical cleaning with chelating agents might be an alternative to mechanical methods. In this study the use of the chelating agent sodium tripolyphosphate (STPP) was examined to determine whether it is effective in discriminating between calcium carbonate and copper patina, and non-corrosive to copper alloys in the presence of air. Comparative experiments with STPP and disodium ethylenediamine-tetraacetate (Na2-EDTA) were carried out on synthetic malachite, cuprite, calcium carbonate, naturally polished malachite surfaces and sheets of bronze and brass. In addition to the properties of the chelating agent, the solubility of the salts and the pH values of the solutions are crucial factors in the removal of compounds of low solubility. The quantity of metal ions dissolved, estimated by atomic absorption spectral analysis and scanning electron microscopy, showed that the calcareous accretions could be removed satisfactorily, but STPP also dissolved constituent parts of the patina, such as malachite and cuprite, and may harm bronze or brass. Compared to Na2-EDTA, STPP is less effective in dissolving calcium carbonate. It is less harmful to the patina and base metal, but may lead to patination of the underlying metal.  相似文献   

13.
《文物保护研究》2013,58(3):191-215
Abstract

Fumigant effects on protein-based materials were examined and compared with those of non-chemical pest-eradicating measures. The responses to six fumigants – methyl bromide, methyl iodide, ethylene oxide, methyl bromide/ethylene oxide mixture, propylene oxide and sulfuryl fluoride – were examined with two controlled atmospheres and a range of thermal treatments, using protein electrophoresis, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermal microscopy (Tmic), thermal gravimetric analysis (TGA), amino acid analysis and X-ray fluorescence (XRF) spectrometry. A model soft-tissue protein, freeze-dried chicken muscle, was shown to be affected by some fumigants, especially methyl bromide, methyl iodide and sulfuryl fluoride (Vikane®). This is the first detailed evidence of chemical alterations of a protein material by fumigants under the common treatment conditions for museum use, especially showing a possibility of protein modification by purer grade sulfuryl fluoride whose definite mechanism of toxicity is still unknown. Residual bromine and iodine were clearly detected by XRF in the muscle specimen that had been fumigated with either methyl bromide or methyl iodide respectively, even after a single fumigation several years earlier. On the other hand, significant change in characteristics of animal glue and new and deteriorated silk textiles were not detected. However, residual bromine and occasionally iodine also were detected in the glue and silk samples fumigated by methyl bromide or methyl iodide several years earlier.  相似文献   

14.
ABSTRACT

Chalconatronite, Na2[Cu(CO3)]2·3H2O, is formed as a corrosion product when copper alloys are exposed to sodium carbonate solutions in the air. This also happens when metals come into contact with corroding soda glass which forms alkaline surface films in reaction with humidity from clean air. More often, substantial amounts of formaldehyde are present indoors which react to formate via the Cannizzarro reaction and accumulate over time in the films. Twenty cases of chalconatronite (including two mentioned in the literature) are reported as occurring on heritage objects with glass in contact with copper alloys: Baroque reliquaries with set glass gems, enamel on metal (sixteenth century and a modern replica of intentionally unstable composition), Christmas tree glass baubles with wires, glass buttons with metal shanks, a glass figure with a wire support, miners’ lamps, and a glass framed daguerreotype. These confirmed identifications might help conservators in investigating similar cases to shed more light on the formation conditions.  相似文献   

15.
《文物保护研究》2013,58(1):25-37
Abstract

Marble specimens were impregnated with epoxy resins by first soaking the specimens in a solvent and then treating them, in steps, with increasing concentrations of the resin in the resin-solvent mixture. This resulted in impregnation to several centimeters’ depth into the specimen. Both impregnated and non-impregnated specimens were subjected to 3000 ppm SO2 atmospheres in a dynamic system. X-ray diffraction and fluorescence studies to determine the deterioration quantitatively, revealed that transformation of the outer layer of non-impregnated marble into primarily calcium sulfite stopped after a maximum of 15 mole percent conversion under normal conditions of humidity. While certain impregnated marble specimens showed significant protection from SO2 attack, other impregnated specimens revealed more reactivity than the controls. A partial explanation of this has been obtained by scanning electron microscopy which showed that the resin films on the surface were perforated. Coatings of certain acrylics provided some additional protection to impregnated specimens.  相似文献   

16.
《文物保护研究》2013,58(5):321-332
Abstract

Historical renders are exposed to several degradation processes that can lead to a wide range of anomalies, such as scaling, detachments, and pulverization. Among the common anomalies, the loss of cohesion and of adhesion are usually identified as the most difficult to repair; these anomalies still need to be deeply studied to design compatible, durable, and sustainable conservation treatments. The restitution of render cohesion can be achieved using consolidating products. Nevertheless, repair treatments could induce aesthetic alterations, and, therefore, are usually followed by chromatic reintegration. This work aims to study the effectiveness of mineral products as consolidants for lime-based mortars and simultaneously as chromatic treatments for pigmented renders. The studied consolidating products are prepared by mixing air lime, metakaolin, water, and mineral pigments. The idea of these consolidating and coloring products rises from a traditional lime-based technique, the limewash, widely diffused in southern Europe and in the Mediterranean area. Consolidating products were applied and tested on lime-based mortar specimens with a low binder–aggregate ratio and therefore with reduced cohesion. A physico-mechanical, microstructural, and mineralogical characterization was performed on untreated and treated specimens, in order to evaluate the efficacy and durability of the treatments. Accelerated aging tests were also performed to assess consolidant durability, when subjected to aggressive conditions. Results showed that the consolidants tested are compatible, effective, and possess good durability.  相似文献   

17.
ABSTRACT

The impact of relative humidity (RH) and temperature variation on the mechanical behaviour of paintings on canvas was investigated, based on the various environmental recommendations that are applied by museums and institutions worldwide. Paint samples were constructed based on the works of twentieth-century artists such as Soulages and Riopelle. The various samples are based on criteria such as paint media, additives, pigment type, canvas type, thickness, type of application, and drying time. Once they are fully dry, paint films behave as elastic, viscoelastic, or viscoplastic materials depending on the chemical nature of their components. These properties, as well as tensile strength, were determined by a series of tensile tests. Other samples were included, originating from discarded oil paintings on canvas from the seventeenth and nineteenth centuries. To carry out mechanical tests under controlled conditions of temperature and RH, a climatic chamber was built around the column of a universal testing machine. Samples were submitted to stress relaxation tests to observe their response to changes in environmental conditions. RH was increased from 20 to 90% and temperature from 15 to 60°C. Reactivity diagrams were drawn based on the results. The endurance limit under mechanical fatigue was determined from the diagrams and helped define the risks associated with each painting type when exposed to the accepted environmental recommendations.  相似文献   

18.
《文物保护研究》2013,58(3):274-282
Abstract

A study of the composition and phase distribution of the corrosion layers on three ferrous objects, excavated at K2 (Bambandyanalo), an archaeological site in South Africa, was conducted. The objective of the study was to obtain information that can contribute to conservation procedures to be performed on the iron artefacts from this site. Examination of cross sections by means of energy-dispersive X-ray spectroscopy coupled to a scanning electron microscope (SEM–EDX), X-ray powder diffraction (XRD), and micro-Raman spectroscopy revealed the same corrosion composition and structure for all the objects under study, namely an internal layer adjacent to the metal surface with ghost inclusions and an external layer containing quartz grains. The study also revealed that the presence of magnetite (Fe3O4), maghemite (γFe2O3), and lepidocrocite (γ-FeOOH) within the internal layer is the only difference between the chemical compositions of iron corrosion products within the two layers. The results also made it possible to retrace the corrosion history during burial and long-term storage.  相似文献   

19.
《文物保护研究》2013,58(4):217-226
Abstract

Many natural and synthetic products have been used for the consolidation of paint layers, but none have been thoroughly tested for this application. This is apparent for most of the synthetic and semi-synthetic adhesives for conservation, many of which are pure polymer resins and dispersions adapted from other industries. They were not specifically formulated with the appropriate properties for conservation, nor do they take advantage of some of the more recent developments in adhesive technology. BEVA® 371 is unique among adhesives used for consolidation treatments, as it is a multi-component mixture and was designed specifically for the conservation field using the best technology available at the time. However, the main focus of the research was its application as a lining adhesive. Thus, optical properties and stability, specifically color stability, were not thoroughly evaluated even though some lining applications that were first recommended could have benefited from this type of investigation. This paper will discuss the development of BEVA® 371, the chemistry, and roles of each component, and address a practical concern about the tack behavior of its replacement formulation, BEVA® 371b.  相似文献   

20.
ABSTRACT

Mechanical properties of aged beeswax were studied by an indirect measurement, using hydrogenated beeswax as a model material. The adequacy of the model was evaluated by comparison of its chemical composition and thermal properties with those of samples of historical beeswax. It was found that the gradual decrease in content of unsaturated compounds in beeswax contributes significantly to changes of its mechanical properties. As a consequence, beeswax artefacts become increasingly prone to mechanical damage during natural ageing. Understanding the difference between mechanical properties of recent and historical beeswax is primarily important from the point of view of safe handling and storage of such artefacts. Besides, this knowledge could help conservation scientists, e. g. when preparing model samples for testing new conservation methods.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号