Protective Green Patinas on Copper in Outdoor Constructions

The last 15 years of research related to atmospheric corrosion and the release of copper to the environment are shortly summarized. Brown and green patinas with high barrier properties for corrosion are gradually evolved on copper at atmospheric conditions. The corrosion process and repeated dry and wet cycles results in a partial dissolution of corrosion products within the patina. Dissolved copper can be released and dispersed into the environment via the action of rainwater, however the major part is rearranged within the patina during drying cycles. The majority of corrosion products formed have a poor solubility, very different from water soluble copper salts. The release process is very slow and takes place independent of patina color. Its extent has only a marginal effect on the adherent patina. Released copper rapidly interacts with organic matter and in contact with different surfaces already in the close vicinity of the building, such as drainage systems, storm water pipes, pavements, stone materials and soil systems. These surfaces all have high capacities to retain copper in the runoff water and to reduce its concentration and chemical form to non-available and non-toxic levels for aquatic organisms.

STRUCTURE OF BLACK PATINA ON THE ANCIENT BRONZE MIRRORS

X-ray diffaction analysis(XRDA)data of the black or brown patina on the surfaces of eight kinds of bronze mirror samples show 4 or 5 broad diffuse peaks which corresponding to almost the same 20 angle, while their matixes does not.These results indicate that those diffuse peaks were produced by the SnO2, microcrystals of 3 ￣5 nm size contained in the black or brown patina.The matrix of unearthed black patina bronze mirror numbered 223, gives strong XRDA diffraction peaks, indicating that there are a large amounts of non-oxidized bronze alloy particles surrounded by SnO2,which shows that the black patinas are not wholly metallic oxides (mainly SnO2),there are also a lot of original alloys of different sizes in grain in the patina.The bright-field image of the black patina sample gives the same result.

贮藏温度及榨汁机等对苹果出汁率的影响

对国光苹果出汁率的影响因素进行了试验研究。结果表明,在0℃贮藏28天出汁率减少了2.95％,贮藏到60天或在15.5℃贮藏28天出汁率则明显降低,比对照分别降低了4.15％和14.5％。压榨时用板框式榨汁机比用螺旋式榨汁机压榨果汁产量高10.725％,冷却沉渣低22％,重复压榨比一次性压榨的果汁产量增加10％～21.9％。0.1％的Pectinex Ultra SP果胶酶处理果浆30～120min比未处理提高果汁产量2.2％～5.1％,可溶性固形物含量提高1.08％～1.35％。

Chemical and Electrochemical Characterization of Artifi cial Sulphate Patina on Bronze

Copper patinas are generally regarded as aesthetically pleasing and are supposed to protect copper against further corrosion. The preparation of artificial sulphate patina on bronzes has been realized by immersing the bronze into CuSO4 solution. The effect of immersion time on the formation of the patina has been investigated. The sulphate patina obtained with immersion time of 500 h in CuSO4 solution consists of fiat area and crystals. The flat area in the patina is mainly made of cuprite, whereas the crystals are mainly composed of brochantite. The electrochemical measurement of sulphate patina in simulated acid rain with pH 3.1 shows that the protective effectiveness of patina decreases with time and the dissolution of patina is the key factor leading to the degradation of patina. The investigation of the formation mechanism of sulphate patina shows that the cuprite layer forms on the surface of bronze in the initial patination. Then, crystal brochantite grows on the surface of cuprite by the oxidation of cuprite and the incorporation of CuSO4 solution.

Determining the Authenticity of Artifacts by Oxygen Isotope Analysis

A technique used to determine the authenticity of artifacts that compares the oxygen isotopic composition of speleothems to the carbonate included within the patina of unprovenanced artifacts is of questionable value. The unprovenanced Jehoash Inscription Tablet and James Ossuary are of potentially immense historical and cultural importance. Nevertheless, they both were rejected by workers based on the oxygen isotope technique which provided the major foundational evidence of forgery in the longest running archaeological trial in Israel. Nevertheless, both these artifacts were determined not to be forged. The initial incongruence between the oxygen isotopes of the speleothems of the Soreq cave (Israel) purported to represent the unique composition of Jerusalem rainfall, and the patina on the artifacts, can be readily explained by the accretion of materials and geo-biochemical processes expected in normal patina formation in the Jerusalem region. The patina formation involves sporadic events in disequilibrium kinetic processes that are opposed to the equilibrium formation of speleothems in a sealed cave. Moreover, 23 of 56 patina samples (41%) on well-documented ancient artifacts from Israel yielded oxygen isotope values greater or lower than the expected speleothem values of -4 δ18O ‰ [PDB] to -6 δ18O ‰ [PDB]. Thus, the speleothem-patina correlation is invalid and the applied oxygen isotopes technique for determining the authenticity of patinas on artifacts is not a useful tool in the authentication of artifacts.

Formation of Black Patina on Bronze Mirrors Caused by Multiphenol

Hot solution of hydroquinone is oxidized by air forming quinone and quinhydrone, both of which have weak oxidizeability, enabling to oxidize metals on the surface of bronze mirror samples forming black and brilliant patina. SEM and electron micro probe analysis show that Cu content is lower than that of the original alloy due to Cu loss; Sn content is higher than the original alloy in patina. This indicates that humic acid is not the substance resulting in making black patina on the bronze mirror surface, but the black patina which produced from hydroquinone solution absence of Si, Al and Mg.

Formation of Black Patina on Bronze Mirrors Caused by Humic Acid

The formation of black patina caused by soil humic acid under different conditions has been studied,and the black, grey and brown shiny surfaces prepared in laboratory have been analysed. The formation of tin-rich shiny black surface on mirrors was the product of the soil corrosion of the bronze mirrors. It is formed by reaction between the alloy and the humic acid in soil, and leaching of copper and lead oxides through a long period of time when the mirrors were buried under the ground. A dense cormsion-resistallt layer on the bronze mirrors consisted predominantly of stannic oxide.

Structure and Formative Mechanism of Black Patina on Bronze Mirrors

The formation of the black patina induced by soil humic asid under different conditions was studied, theblack, grey and brown colored shiny surfaces prepared in laboratory were analyzed. As a result the formation oftin-rich shiny black surface on bronze mirrors is the product of soil corrosion of the bronze mirrors. The patina isformed by reection between the alloy and the humic acid in soil, and leaching of copper and lead oxides through along period time when the mirrors were buried under the ground leaving a dense compact corrosion-resistant layerconsisted predominantly of stannic oxide microcrystal.

Quantitative Analysis Method for Corrosion and Patina Progression on Plumbing Components during Long-Term Connection Leaks from Potable Water Supply Systems

The modern field of Forensic Engineering evaluates the origin, cause, and duration of failed building components. As many failed components are subject to insurance claims and legal probes, a scientific methodology for evaluating such events is inherently valuable. Due to the potential for widespread interior finish damage, failed plumbing supply components are commonly encountered during forensic evaluations. Plumbing pipes?themselves and properly soldered fittings rarely fail. Consequently, many failures correspond to mechanical fittings which form connections from pipes to plumbing fixtures.?The results of this study provide a scientific methodology to evaluate the duration of connection leaks by quantifying the extent of corrosion, patina, and accumulated deposits on various components?by creating and evaluating slow plumbing supply component connection leaks.

The Authenticity of the James Ossuary

An archaeometric analysis of the James Ossuary inscription “James Son of Joseph Brother of Jesus” strengthens the contention that the ossuary and its engravings are authentic. The beige patina can be observed on the surface of the ossuary, continuing gradationally into the engraved inscription. Fine long striations made by the friction of falling roof rocks continuously crosscut the letters. Many dissolution pits are superimposed on several of the letters of the inscription. In addition to calcite and quartz, the patina contains the following minerals: apatite, whewellite and weddelite (calcium oxalate). These minerals result from the biogenic activity of microorganisms that require a long period of time to form a bio-patina. Moreover, the heterogeneous existence of wind-blown microfossils (nannofossils and foraminifers) and quartz within the patina of the ossuary, including the lettering zone, reinforces the authenticity of the inscription.

Corrosion kinetics and patina evolution of galvanized steel in a simulated coastal-industrial atmosphere

The corrosion kinetics and patina(corrosion products) layer evolution of galvanized steel submitted to wet/dry cyclic corrosion test in a simulated coastal-industrial atmosphere was investigated. The results show that zinc coating has a greater corrosion rate during the initial period and a lower corrosion rate during the subsequent period, and the patina composition and structure can greatly affect the corrosion kinetics evolution of zinc coating. Moreover, Zn5(OH)6(CO3)2 and Zn4(OH)6 SO4 are identified as the main stable composition and exhibit an increasing relative amount;while Zn12(OH)15Cl3(SO4)3 cannot stably exist and diminish in the patina layer as the corrosion develops.

Bacteriological challenges to asbestos cement water distribution pipelines

Asbestos cement （AC） pipes were commonly installed in the drinking water distribution systems from the mid 1920s to the late 1980s. In recent years, an increase in the number of water main breaks has occurred in the AC portions of some pipe networks, which can be partially attributed to the corrosion of the aged pipes. This study evaluated the potential role that microorganisms may have played in the degeneration and failure of AC pipes. In this study, a fresh AC pipe section was collected from the distribution network of the City of Regina, Canada and examined for microbiological activities and growth on inside surfaces of pipe sample. Black slime bacterial growths were found to be attached to inner pipe surfaces and a distinctively fibrous internal coating （patina） with iron oxides was formed over the time. The microbial populations inside the patina and the black slime were tested with BART^TM testers. Heterotrophic aerobic bacteria （HAB） and slime forming bacteria （SLYM） dominated in both the black growths and inside the patina. Iron related bacteria, denitrification bacteria and sulfate reducing bacteria were also commonly present. Microbial challenge assays were conducted by submerging the cut segments of the AC pipe into selected bacterial cultures for a period of 10 days under both aerobic and anaerobic environments. Weight changes were determined and the surface morphology was examined for each of the assayed pipe segments. Results indicated that acid producing bacteria, SLYM and HAB could facilitate the pipe weight loss under anaerobic environments.

漆画创作中patina植入与表现

天然大漆是一种有着久远历史的材料,而漆画却是近现代出现的绘画种类,但受着漆器根深蒂固的形象的影响,漆画的整体面貌相对传统。无论是对材料的运用和技法的要求,都时时刻刻离不开漆器造型的束缚,甚至对漆画的表面平整度或是光亮度提出了严苛的要求,这显然违背了艺术创作的本意,本文就漆画创作材料的植入与表现展开话题,以patina的技法为主要研究,结合我自己的漆画创作来具体的探讨这个问题。在我个人的漆画作品(图1)中植入了铜片,