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. 1999 年 8 月 2 日对于英国 Cirencester 小镇而言是一个特别热的日子，Bishops 街一家购物中心的 巨型钢化玻璃屋顶在毫无预兆的情况下就破碎了。 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. Pilkington 的一家巨型玻璃制造商（该破碎玻璃的制 造厂商）对玻璃碎片进行了分析，他们发现这次事件的罪魁祸首是玻璃内部的微小硫化镍晶体。

‘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. “玻璃行业已经意识到了问题的存在，”GGF 协会主席说道。 But he insists that cases are few and far between. 但是他坚称，这一案例实属罕见。 'It's a very rare phenomenon,' he says. “这是一种很少见的现象，”他说道。

Others disagree. 其他人却不这样看。 ‘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. “平均来说，我每个月都会看到一两个建筑物上会有玻璃因为硫化镍晶体问题而破碎，”Barrie Josie 说道，他是一位 Bishops 街事件调查小组的成员之一。 Other experts tell of similar experiences. 其他专家也讲述了类似经历。 Tony Wilmott of London-based consulting engineers Sandberg, and Simon Armstrong at CladTech Associates in Hampshire both say they know of hundreds of cases. Tony Wilmott 和 Simon Armstrong 都说他们知道几百个类似案例。 'What you hear is only the tip of the iceberg,’ says Trevor Ford, a glass expert at Resolve Engineering in Brisbane Queensland. “你听到的只是冰山一角，”一位在布里斯班昆士兰的解决工程的玻璃专家Trevor Ford 说。 He believes the reason is simple: 'No-one wants bad press. 他觉得原因很简单：“没有人喜欢坏消息。”

Toughened glass is found everywhere, from cars and bus shelters to the windows, walls and roofs of thousands of buildings around the world. 钢化玻璃随处可见，例如汽车玻璃、窗户以及世界各地的数以百万计的建筑物上的玻璃幕墙和玻璃屋顶。 It's easy to see why. 采用玻璃的原因也很简单。 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. 这种玻璃的强度是普通玻璃的五倍，而且当钢化玻璃破碎的时候， 会产生小型块状碎片，而不会产生大块的锋利碎片。 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. 建筑师热衷于使用钢化玻璃，因为大块的钢化玻璃板很容易拼凑出整面的透明幕墙，而且也可以用类似的方法做成天花板和地板。

It is made by heating a sheet of ordinary glass to about 620°C to soften it slightly, allowing its structure to expand, and then cooling it rapidly with jets of cold air. 钢化玻璃的制造过程是：将一块普通玻璃加热到 620℃，以使其轻微软化，结构膨胀，然后用冷水喷射使其快速冷却。 This causes the outer layer of the pane to contract and solidify before the interior. 这使得玻璃板外层先于内层收缩和固化。 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. 当内层最终固化并且收缩时，内层会对外层施加某种拉力，使之处于恒久压力的作用中，从而产生玻璃内部的张力。 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. 裂缝在处于压力作用下的物质中最容易扩散，而压力要克服玻璃表面的张力才会导致玻璃破碎，因此钢化玻璃具有防裂效果。

The problem starts when glass contains nickel sulphide impurities. 当玻璃中存在硫化镍之类的杂质时，就会出现问题。 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. 制造玻璃的原材料中通常会含有微量的镍和 硫，在熔融状态的玻璃中添加的镍合金也会使玻璃中含有镍。 As the glass is heated, these atoms react to form tiny crystals of nickel sulphide. 随着玻璃被加热，这些原子就会发生反 应，形成微小的硫化镍晶体。 Just a tenth of a gram of nickel in the furnace can create up to 50,000 crystals. 一个熔炉里含有十分之一克的镍，就足以产生 50 000 个晶体。

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. 这些晶体以两种形式存在：一种是致密结构，称为 AP，这种结构在高温下仍然稳定；另一种是非 致密结构，称为 BP，这种钢结构在常温下稳定。 The high temperatures used in the toughening process convert all the crystals to the dense, compact alpha form. 钢化工艺中所使用的高温把所有的晶体都变成了致 密、高强度的 AP 状态。 But the subsequent cooling is so rapid that the crystals don’t have time to change back to the beta phase. 但是随后的冷却过程过快，导致晶体结构来不及回到 BP 状态。 This leaves unstable alpha crystals in the glass, primed like a coiled spring, ready to revert to the beta phase without warning. 这就使得不稳 定的 AP 晶体留在了玻璃中，就像被压缩的弹簧一样，随时在毫无征兆的情况下回到 BP 状态。

When this happens, the crystals expand by up to 4%. 当这个过程发生时，晶体颗粒会膨胀 4%。 And if they are within the central, tensile region of the pane, the stresses this unleashes can shatter the whole sheet. 如果这些晶体可以位于中央张力最大的位置，它们所释 放出来的张力可以使整块玻璃破碎。 The time that elapses before failure occurs is unpredictable. 玻璃要多久才会破碎，这是无法预测的。 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. 也许出厂后几个月就会发 生，也许几十年后才发生，但是阳光的加热也会使这一过程加速发生。 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. 具有讽刺意味的是，Graham Dodd 说，由于硫化镍原因而导致破碎的钢化玻璃中，使用年份最长的位于Lancashire郡Lathom 市的 Pilkington 玻璃研究中心。 The pane was 27 years old. 那块玻璃足足用了 27 年之久。

Data showing the scale of the nickel sulphide problem is almost impossible to find. 我们很难发现数据来证明硫化镍所造成的问题的规模。 The picture is made more complicated by the fact that these crystals occur in batches. 硫化镍问题的大量涌现使得事情更加复杂 化。 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. 平均来说，即便 7 吨玻璃中只有一吨含有硫化镍，即便你所在的建筑物中只有一次硫化镍事件是 你亲眼见过的，那也意味着有问题的不止是一块玻璃。 Josie says that in the last decade he has worked on over 15 buildings with the number of failures into double figures. Josie 说，在过去的十年中，他研究了 15 座建 筑，玻璃破碎事件的数量已经翻番。

One of the worst examples of this is Waterfront Place, which was completed in 1990. 最严重的一次发生在 Waterfront Place，这栋建筑建成于 1990 年。 Over the following decade the 40-storey Brisbane block suffered a rash of failures. 在随后的十年中，这栋位于布里 斯班的 40 层大楼遭遇了一系列的玻璃破碎事件。 Eighty panes of its toughened glass shattered due to inclusions before experts were finally called in. 在专家介入之前，有八十块玻璃因为含硫化镍而破 碎。 John Barry, an expert in nickel sulphide contamination at the University of Queensland, analysed every glass pane in the building. John Barry 分析了该建筑物中的每一块玻璃。 Using a studio camera, a photographer went up in a cradle to take photos of every pane. 通过使用专业相机，摄影师在吊车内拍摄了每块玻璃 的相片。 These were scanned under a modified microfiche reader for signs of nickel sulphide crystals. 随后，这些照片被放在了经过改装的微缩胶片机上进行硫化镍晶体扫描。 'We discovered at least another 120 panes with potentially dangerous inclusions which were then replaced,' says Barry. “我们发现至少还有 120 块玻璃有潜在危险，这些玻璃后来被更换了，”Barry 说，“这个过程非常昂贵，也很耗时，大概用了六个月时间才完成。 'It was a very expensive and time-consuming process that took around six months to complete. ”尽管这个项目花去了 160 万澳元，但是另一个方案（重新装修整栋大厦）的花费大 概将是这个数字的十倍。 6 million (nearly £700,000), the alternative - recladding the entire building - would have cost ten times as much.