剑桥雅思5 Test 4阅读Passage 2原文翻译 Flawed Beauty: the problem with toughened glass 钢化玻璃的问题
剑桥雅思5 Test 4 Passage 2原文翻译
On 2nd August 1999, a particularly hot day in the town of Cirencester in the UK, a large pane of toughened glass in the roof of a shopping centre at Bishops Walk shattered without warning and fell from its frame. When fragments were analysed by experts at the giant glass manufacturer Pilkington, which had made the pane, they found that minute crystals of nickel sulphide trapped inside the glass had almost certainly caused the failure.
‘The glass industry is aware of the issue,’ says Brian Waldron, chairman of the standards committee at the Glass and Glazing Federation, a British trade association, and standards development officer at Pilkington. But he insists that cases are few and far between. ‘It’s a very rare phenomenon,’ he says.
Others disagree. ‘On average I see about one or two buildings a month suffering from nickel sulphide related failures,’ says Barrie Josie, a consultant engineer involved in the Bishops Walk investigation. Other experts tell of similar experiences. Tony Wilmott of London-based consulting engineers Sandberg, and Simon Armstrong at CladTech Associates in Hampshire both say they know of hundreds of cases. ‘What you hear is only the tip of the iceberg,’ says Trevor Ford, a glass expert at Resolve Engineering in Brisbane, Queensland. He believes the reason is simple: ‘No-one wants bad press.’
其他人不同意。参与主教大道文章来自老烤鸭雅思调查的顾问工程师巴里·乔西（Barrie Josie）表示：“平均而言，我每个月都能看到大约一两个建筑物遭受与硫化镍有关的故障。” 其他专家讲述了类似的经历。伦敦咨询工程师Sandberg的Tony Wilmott 和汉普郡的CladTech Associates的Simon Armstrong 都说他们知道数百起案件。“你听到的仅仅是冰山一角，”特雷弗·福特说。他是昆士兰州布里斯班Resolve Engineering公司的玻璃专家。他认为原因很简单：“没有人想要坏新闻。”
Toughened glass is found everywhere, from cars and bus shelters to the windows, walls and roofs of thousands of buildings around the world. It’s easy to see why. This glass has five times the strength of standard glass, and when it does break it shatters into tiny cubes rather than large, razor-sharp shards. Architects love it because large panels can be bolted together to make transparent walls, and turning it into ceilings and floors is almost as easy.
It is made by heating a sheet of ordinary glass to about 620℃ to soften it slightly, allowing its structure to expand, and then cooling it rapidly with jets of cold air. This causes the outer layer of the pane to contract and solidify before the interior. When the interior finally solidifies and shrinks, it exerts a pull on the outer layer that leaves it in permanent compression and produces a tensile force inside the glass. As cracks propagate best in materials under tension, the compressive force on the surface must be overcome before the pane will break, making it more resistant to cracking.
它是通过将一片普通玻璃加热到620 ℃ 使其略微软化，结构膨胀，然后用冷空气迅速冷却而制成的。这导致窗格玻璃的外层在内部之前收缩和固化。当内部最终固化并收缩时，它会在外层上施加拉力，使它处于永久压缩状态，并在玻璃内部产生张力。由于裂纹在张力下在材料中传播最好，因此必须在玻璃破裂之前克服表面上的压缩力，以使其更抗破裂。、
The problem starts when glass contains nickel sulphide impurities. Trace amounts of nickel and sulphur are usually present in the raw materials used to make glass, and nickel can also be introduced by fragments of nickel alloys falling into the molten glass. As the glass is heated, these atoms react to form tiny crystals of nickel sulphide. Just a tenth of a gram of nickel in the furnace can create up to 50,000 crystals.
These crystals can exist in two forms: a dense form called the alpha phase, which is stable at high temperatures, and a less dense form called the beta phase, which is stable at room temperatures. The high temperatures used in the toughening process convert all the crystals to the dense, compact alpha form. But the subsequent cooling is so rapid that the crystals don’t have time to change back to the beta phase. This leaves unstable alpha crystals in the glass, primed like a coiled spring, ready to revert to the beta phase without warning.
When this happens, the crystals expand by up to 4%. And if they are within the central, tensile region of the pane, the stresses this unleashes can shatter the whole sheet. The time that elapses before failure occurs is unpredictable. It could happen just months after manufacture, or decades later, although if the glass is heated – by sunlight, for example – the process is speeded up. Ironically, says Graham Dodd, of consulting engineers Arup in London, the oldest pane of toughened glass known to have failed due to nickel sulphide inclusions was in Pilkington’s glass research building in Lathom, Lancashire. The pane was 27 years old.
Data showing the scale of the nickel sulphide problem is almost impossible to find. The picture is made more complicated by the fact that these crystals occur in batches. So even if, on average, there is only one inclusion in 7 tonnes of glass, if you experience one nickel sulphide failure in your building, that probably means you’ve got a problem in more than one pane. Josie says that in the last decade he has worked on over 15 buildings with the number of failures into double figures.
One of the worst examples of this is Waterfront Place, which was completed in 1990. Over the following decade the 40-storey Brisbane block suffered a rash of failures. Eighty panes of its toughened glass shattered due to inclusions before experts were finally called in. John Barry, an expert in nickel sulphide contamination at the University of Queensland, analysed every glass pane in the building. Using a studio camera, a photographer went up in a cradle to take photos of every pane. These were scanned under a modified microfiche reader for signs of nickel sulphide crystals. ‘We discovered at least another 120 panes with potentially dangerous inclusions which were then replaced,’ says Barry. ‘It was a very expensive and time-consuming process that took around six months to complete.’ Though the project cost A$1.6 million (nearly ￡700,000), the alternative – re-cladding the entire building – would have cost ten times as much.
最糟糕的例子之一是1990年建成的海滨广场（Waterfront Place）。在随后的十年中，布里斯班40层高的大楼遭受了多次事故。在专家最终被召集过来之前，其八十块玻璃钢化玻璃都因为杂质而破裂了。约翰·巴里，昆士兰硫化物污染专家，分析了建筑的每个玻璃面板。摄影师在围栏里用摄影棚的照相机为每块窗格拍照。这些在改进的微缩胶片阅读器上进行扫描以寻找硫化镍晶体迹象。巴里说：“我们至少发现了120块带有潜在危险杂质的玻璃，然后将其更换。这是一个非常昂贵而且耗时的过程，大约需要六个月才能完成。” 虽然工程高达 160万澳元（约合700,000 英镑），其替代方案-重新覆盖整个建筑物-成本将是这的十倍。