仿生合成石质文物二氧化硅保护膜的研究

由于二氧化硅仿生材料具有优越的耐候性,与基底石材相容性好,合成条件的温和性及对环境无污染等优点,为此制备了二氧化硅防护膜。室温下利用CTAB自组装体为模板来调控Na2SiF6水解,在石材表面制备出具有优良性能的SiO2膜,并对膜进行了XRD、SEM分析表征。经过保护处理的石材表面清洁、透明,具有突出的抵抗酸碱性能。生成的保护膜具有良好的透气性,而吸水性有所下降。另外,该保护膜还显示出优良的抵抗高、低温,耐磨,及与基底结合紧密等性能。上述研究表明,仿生SiO2膜将会对石质文物起到更好的保护作用。     

纤维素-壳聚糖共聚物对石材试样保护的探索研究

为研究纤维素-壳聚糖共聚产物对石质文物封护保护的可行性,采用自由基聚合法,以过硫酸钾为引发剂,将醋酸丁酸纤维素(CAB)与壳聚糖进行接枝共聚,制备了纤维素-壳聚糖接枝共聚物。同时研究了纤维素和壳聚糖接枝共聚反应的最佳条件:引发剂K2S2O8浓度1.5mmol/L,预处理温度40℃,时间2h,纤维素与壳聚糖的质量比为2:1,反应温度50℃,反应时间8h,交联剂0.12mL,总液体积100mL。分析了纤维素-壳聚糖用量对石质文物封护材料的性能影响,并且对石材试样进行模拟试验,测试分析了色差度、光泽度、接触角、附着力、透气性和耐老化等性能指标,并采用红外光谱、扫描电镜对试样进行表征。结果表明,经纤维素-壳聚糖接枝聚合物浓度为15%的封护材料保护后,石材试样保持了原有的质感、光泽、颜色,并且憎水性、耐老化性等性能得到了大幅提高,对石材试样具有良好的封护效果,为天然高分子在纸质文物保护中的应用开辟了广阔的前景。     

古代壁画、彩绘显现剂应用机理和性能研究

针对粘结硬质、钙化土锈的壁画和彩绘在保护修复中使用的去除剂和显现加固剂复合应用后对其性能进行了研究测试。从光学角度对明胶膜和加样后膜折射率进行测试,对土锈剩余层粒径与厚度进行测试,又从耐久性、柔韧性等方面对两种试剂复合用的模拟壁画进行了系统评价。结果表明:两种膜的折射率几乎相同,当土锈剩余层粒径在120μm以内,厚度在70μm内的土粒都可以通过显现加固剂进行显现,恢复其古朴原貌,且不触及颜料层。复合应用后对模拟样板老化后性能测试,数据显示各方面性能良好。     

有机-无机复合疏水型二氧化硅涂层制备及性能

为研究制作保护石质文物的加固材料,采用溶胶-凝胶法,以两种有机硅材料(正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MTES))为共同前驱体,少量正辛胺为催化剂,聚二甲基硅氧烷(PDMS)(方法 1)或硅烷偶联剂KH-570(方法 2)为有机改性剂,制备了有机-无机复合疏水型Si O2涂层。通过红外光谱(FT-IR)、扫描电镜(SEM)和水接触角(WCA)来表征在砖块表面形成的SiO_2膜层化学组成、表面形貌以及疏水性能,然后再通过测试砖块加固前后外观、吸水性能和孔隙率的变化来验证实际加固效果。结果表明,两种方法均可以制备骨架带-CH3基团的SiO_2溶胶。采用方法 1(添加前驱体质量10%的PDMS)或者方法 2(MTES/TEOS质量比为2),加固后的砖块对水接触角均超过140°,毛细吸水率降低到未处理时的1%~2%,并且砖块的色差和光泽度改变较小。通过耐候性能测试表明,方法 2的保护效果相对较好,说明用此种方法合成的疏水性二氧化硅涂层可以作为砖块加固材料。     

常熟赵用贤宅无地仗层彩绘的保护研究

赵用贤宅彩绘是江苏明代无地仗层彩绘的重要遗物。为对其进行保护,采用XRD、FT-IR、EDS及视频显微镜等检测分析彩绘成分和结构层次,较为成功地解决了旧木材内油溶性成分极易因溶剂作用带出,部分彩绘上人为涂饰石灰、涂料的去除等技术难点。同时采用接近原胶粘剂性能的复合天然材料(脱色明胶和壳聚糖复配物)加固彩绘,并以溶剂型有机硅材料封护保护。结果表明,保护处理后不仅有效地延长了加固材料的寿命,同时符合可再处理原则。     

氟碳涂料在铁质文物封护中的应用研究

氟碳涂层有良好的耐候性、抗腐蚀性,作为文物封护材料在我国已经得到了一些应用,然而按照工业方法直接实施封护,不能很好满足文物封护保护低光泽度、可再处理等特殊要求。为此,对氟碳涂料在铁质文物保护中的实施工艺进行了研究。研究了一系列氟碳涂层的封护性能,测试了涂层的机械性能、防腐性能、耐候性能和热性能,使用红外光谱对暴晒前后的涂层进行了分析,结果表明:在氟碳涂料中添加纳米二氧化硅和采用复合涂层可以有效的保护室外铁质文物,二氧化硅的加入提高了涂层的热稳定性。     

一类潜在的石质文物表面防护材料:仿生无机材料

仿生技术已经越来越广泛地应用于各个领域 ,包括生物医学材料、纳米材料、薄膜材料和多孔材料等等。在一些石质文物表面发现了一种以草酸钙为主要成分的致密的生物矿化膜 ,以及一种磷酸钙类薄膜 ,使人们看到了仿生技术在文物保护领域的应用前景。本文指出了目前石质文物保护材料的不足之处 ,介绍了一些仿生无机材料的优点和合成方法 ,探讨了这些新材料在文物保护方面应用的可能性。     

石质文物表层工程性能保护材料适宜性评价——以羊山造像及摩崖题刻为例

石质文物表层工程性能保护是这类文物保护的重要科学问题,保护材料选择是表层工程性能保护的关键技术应用难点。基于对浙江羊山造像与摩崖题刻表层保护材料应用效果系统进行的实验室测试、分析,通过对优选的5种保护材料的基本性质、使用浓度、色差、附着力、接触角、吸水率及多个耐久性指标的测试,根据测试结果得出保护材料的各方面性能评价指标研究结果,显示水性纳米二氧化硅复合氟碳乳液和油性聚硅氧烷具备保护适宜性。     

应用电位活化理论研究青铜器的腐蚀与保护

应用电位活化理论分析和阐述了青铜器腐蚀的观点和防护理念。对青铜器腐蚀的全过程提出了致密膜保护期、保护膜破坏局部腐蚀期和小孔腐蚀粉状锈加速期三个阶段的看法。用高效钝化保护剂对处于不同腐蚀阶段的青铜器保护膜进行修复和改性 ,结果表明 ,理论腐蚀电阻RC 从 10 5Ω提高到 10 7Ω ,并具有可间断涂覆、可回复的特点 ,可应用于青铜文物的保护试验。     

Parylene膜层对青铜文物的保护研究

如何对青铜文物进行更好的保护,研究发现性能优越的封护材料是文物保护界关注的问题。我们通过对Parylene膜层性能的研究并与其它常用涂层材料分析比对,认为使用Parylene涂敷技术对青铜文物进行涂敷封护,特别是对一些器形复杂,器物的内部表面没有暴露,常用保护涂层不便实施的文物,该涂敷技术是一种理想的方法。     

Evidence for SiO2‐NaCl complexing in H2O‐NaCl solutions at high pressure and temperature

Experimental studies reveal complex dissolution behavior of quartz in aqueous NaCl solutions at high temperature and pressure, involving variation from salting‐in to salting‐out that changes with temperature, pressure, and salt concentration. The behavior is not explainable by traditional electrostatic theory. An alternative hypothesis appeals to complexing of SiO₂ with NaCl and can explain the observations. However, the hypothesis of complexing, as previously applied, is inadequate in several respects: it neglects polymerization of solute silica, regards the SiO₂‐NaCl hybrid complex(es) as anhydrous, which seems unlikely, and invokes an incorrect stoichiometry of the hydrated silica monomer, now known to be Si(OH)₄?2H₂O. These neglected features can be incorporated into the complexing model in a revised formulation based on a simple thermodynamic analysis using existing quartz solubility data. The analysis leads to a quasi‐ideal solution model with silica monomers, dimers, and two distinct hydrous SiO₂‐NaCl hybrid complexes with overall NaCl:H₂O = 1:6, one Na‐bearing and one Cl‐bearing. Their (equal) molar concentrations (X_hc) are governed by a pressure‐ and temperature‐dependent equilibrium constant, , where a_Nacl and are the respective activities of the solvent components. The stability of the hybrid complexes (i.e., their concentration) is very sensitive to H₂O activity. The entire set of experimental quartz‐solubility data at 700°C, 1–15 kbar, is reproduced with high fidelity by the expression (P is pressure in kbar), including the transition from low‐pressure salting‐in to high pressure salting‐out. The results indicate that hybrid SiO₂‐NaCl complexes are the main hosts for dissolved silica at NaCl concentrations greater than 6 wt%, which are likely common in crustal fluids. At higher temperatures, approaching the critical end point in the system SiO₂‐H₂O, the model becomes progressively inaccurate, probably because polymers higher than the dimer become significant as SiO₂ concentration increases.     

Decreasing CO2 partial pressure triggered Mg–Fe–Ca carbonate formation in ancient Martian crust preserved in the ALH84001 Meteorite

We retrace hydrogeochemical processes leading to the formation of Mg–Fe–Ca carbonate concretions (first distinct carbonate population, FDCP) in Martian meteorite ALH84001 by generic hydrogeochemical equilibrium and mass transfer modeling. Our simple conceptual models assume isochemical equilibration of orthopyroxenite minerals with pure water at varying water‐to‐rock ratios, temperatures and CO₂ partial pressures. Modeled scenarios include CO₂ partial pressures ranging from 10.1325 to 0.0001 MPa at water‐to‐rock ratios between 4380 and 43.8 mol mol^?1 and different temperatures (278, 303 and 348 K) and enable the precipitation of Mg–Fe–Ca solid solution carbonate. Modeled range and trend of carbonate compositional variation from magnesio‐siderite (core) to magnesite (rim), and the precipitation of amorphous SiO₂ and magnetite coupled to magnesite‐rich carbonate are similar to measured compositional variation. The results of this study suggest that the early Martian subsurface had been exposed to a dynamic gas pressure regime with decreasing CO₂ partial pressure at low temperatures (approximately 1.0133 to 0.0001 MPa at 278 K or 6 to 0.0001 MPa at 303 K). Moderate water‐to‐rock ratios of ca. 438 mol mol^?1 and isochemical weathering of orthopyroxenite are additional key prerequisites for the formation of secondary phase assemblages similar to ALH84001’s ‘FDCP’. Outbursts of water and CO_2(g) from confined ground water in fractured orthopyroxenite rocks below an unstable CO₂ hydrate‐containing cryosphere provide adequate environments on the early Martian surface.     

The Chemical Composition and Production Area of Early Western Zhou Proto‐Porcelain Unearthed from Yejiashan Cemetery,Suizhou, China

The bodies and glazes of 27 early Western Zhou proto‐porcelain samples from Yejiashan cemetery, Hubei Province, were analysed using LA‐ICP–AES, SEM, XRD, a thermal expansion instrument and other analytical methods. The results indicated that the bodies of all samples were characterized by high silicon and low aluminium, and were made with porcelain stone raw materials found in the south of China. The glazes are typical of high‐temperature calcium glazes of the CaO (MgO) – K₂O (Na₂O) – Al₂O₃ – SiO₂ series, with relatively high Mn and P content, which was probably caused by the addition of plant ashes. The physical properties and phase compositions of Yejiashan proto‐porcelain show that firing processes were still in the early stages of development in ancient China. Multivariate statistical analyses indicated that Yejiashan proto‐porcelain might have come from the Deqing area, in Zhejiang Province. These results provide new archaeological evidence for research on issues related to material flow in the Western Zhou dynasty.     

Chemical analysis of 17th century Millefiori glasses excavated in the Monastery of Sta. Clara-a-Velha,Portugal: comparison with Venetian and façon-de-Venise production

A set of ten Millefiori glass fragments dating from the 17th century, originated from archaeological excavations carried out at the Monastery of Sta. Clara-a-Velha (Coimbra, Portugal), were characterized by X-ray electron probe microanalysis (EPMA), Raman microscopy and UV–Visible absorption spectroscopy. All glasses are of soda-lime-silica type. The use of coastal plant ash is suggested by the relatively high content of MgO, K₂O and P₂O₅, as well as by the presence of chlorine. Tin oxide or calcium antimonate were the opacifiers used in the opaque glasses, cobalt in the blue glasses, copper in the turquoise glasses, iron in the yellow and greenish glasses, and iron and copper were found in the opaque red and aventurine glasses. Based on the concentrations of alumina and silica four different sources of silica were identified, allowing the classification of the glasses into the following compositional groups: low alumina (<2 wt%), which includes a sub-group of cristallo samples with SiO₂ > 70 wt%, medium alumina (2–3 wt%), high alumina (3–6 wt%) and very high alumina (>6 wt%). Comparison with genuine Venetian and façon-de-Venise compositions showed that two fragments are of Venetian production, one of Venetian or Spanish production and the remaining are of unknown provenance. In two fragments the glass of the decoration is probably Venetian or Spanish but the glass used in the body is also of unknown provenance.     

A scientific study of Choson white ware: early porcelain from a royal kiln at Kwangju Usanni

Scientific study of kiln site no. 9 at Usanni, one of the earliest royal Kwangju kiln complexes in operation (from the early 15th to the early 16th century), shows that the technological expertise used to produce white ware was inherited from the celadon technology of the Koryo dynasty. The body material, of low Al₂O₃ and high SiO₂ content, is based on porcelain stone. Such a material, with almost no titanium and a low level of iron, was a rediscovery of the white ware material used earlier at the Sori kiln from the 9th century through to the 11th century. Ash continued to be one of the major ingredients of the glaze, and wares were fired in much the same way as the Koryo celadon, in kilns constructed of mud and rocks and in two steps. The Confucian philosophy and aesthetic of frugality and simplicity adopted from the Ming dynasty onwards by the new government acted as the catalyst for the successful ascent of the new technology.     

Geochemistry and origin of natural gases dissolved in brines from gas fields in southwest Japan

Previous geochemical studies indicated that most natural gases dissolved in brines in Japan are of microbial origin, consisting of methane produced via carbonate reduction. However, some of those from gas fields in southwest Japan contain methane relatively enriched in ¹³C, whose origin remains to be clarified. To address this issue, chemical and isotopic analyses were performed on natural gases and brines from the gas fields in Miyazaki and Shizuoka prefectures, southwest Japan. Methane isotopic signatures (δ¹³C ≈ ?68‰ to ?34‰ VPDB; δ²H ≈ ?183‰ to ?149‰ VSMOW) suggest that these gases are of microbial (formed via carbonate reduction) or of mixed microbial and thermogenic origin. The relatively high δ²H‐CH₄ values and their relationship with the δ²H‐H₂O values argue against the possibility of their formation via acetate fermentation. The δ¹³C‐CO₂ values (≈?5‰), together with the slope of the correlation between δ²H‐CH₄ and δ¹³C‐CH₄ (Δδ²H‐CH₄/Δδ¹³C‐CH₄ ≈ 1), contradict the possibility of their formation via carbonate reduction followed by partial oxidation by methanotrophs. The ³He/⁴He ratios of the gases from Miyazaki (≈0.11–1.3 Ra) and their low correlation with δ¹³C‐CH₄ values do not support an abiogenic origin. It is inferred therefore that the high δ¹³C‐CH₄ values of natural gases dissolved in brines from gas fields in southwest Japan are indications of the contribution of thermogenic hydrocarbons, although whether abiogenic hydrocarbons contribute significantly to the gases from Shizuoka requires further investigation. This study has clarified that, for the future exploration of natural gases in southwest Japan, we should adopt the strategies for conventional thermogenic gas accumulations, such as checking the content, type and maturity of organic matter in the underlying sedimentary rocks.     

Fluid environment for preservation of pore spaces in a deep dolomite reservoir

Well TS1 reveals many uncemented pores and vugs at depths of more than 8000 m in a deep Cambrian dolomite reservoir in the Tarim Basin, northwestern China. The fluid environment and mechanism required for the preservation of reservoir spaces have yet not been well constrained. Carbon, oxygen, and strontium isotope compositions and fluid inclusion data suggest two types of fluids, meteoric water and hydrothermal fluid, affecting the Lower Paleozoic carbonate reservoirs in the Tarim Basin. Based on simulation using a thermodynamic model for H₂O‐CO₂‐NaCl‐CaCO₃ system, meteoric water has the ability to continuously dissolve carbonate minerals during downward migration from the surface to deep strata until it reaches a transition depth, below which it will begin to precipitate carbonate minerals to fill preexisting pore spaces. In contrast, hydrothermal fluid has the ability to dissolve carbonate in deep strata and precipitate carbonate in shallow strata during upward migration. Based on the dissolution–precipitation characteristics of the two types of fluids, the ideal fluid environment for the preservation of preexisting reservoir spaces occurs when carbonate reservoir is neither in the CaCO₃ precipitation domain of meteoric water nor in the CaCO₃ precipitation domain of hydrothermal fluid. Taking the Lower Paleozoic carbonate reservoirs in the north uplift area as an example, the spaces in the deep Cambrian dolomite reservoir near well TS1 were seldom filled because thick Ordovician deposits blocked meteoric water from migrating downward into the Cambrian dolomite reservoir and because the Cambrian dolomite reservoir has been in the domain of hydrothermal dissolution since the Permian. The deep carbonate layers in basins elsewhere with a similar fluid environment may have high uncemented porosity and consequently have good hydrocarbon exploration potential.     

Chemical and lead isotope analysis of some lead-barium glass wares from the Warring States Period,unearthed from Chu tombs in Changde City,Hunan Province,China

In the context of the present study, we have conducted chemical and lead isotope analyses on twelve ancient glass samples unearthed from Chu tombs in Changde City, Hunan Province. The results of the chemical analysis of these samples show that all samples are PbO–BaO–SiO₂ glasses, thus indicating that they are all traditional ancient Chinese glasses. The chemical results also suggest that all Bi wares may either share a common source or were produced according to similar recipes. In turn, the eye beads are different from the Bi wares for their distinct chemical composition. The chemical results indicate that silica, lead-bearing material, barium-bearing material, and sodium/lime-bearing material are the main independent components of the raw materials employed in the production of these glass wares.