tailieunhanh - IELTS Academic Reading Sample 83 - Flawed Beauty the problem with toughened glass

Để đạt kết quả cao trong kì thi sắp tới, các bạn có thể tham khảo và tải về IELTS Academic Reading Sample 83 - Flawed Beauty the problem with toughened glass được chia sẻ dưới đây để có thêm tư liệu ôn tập, luyện tập giải đề thi nhanh và chính xác giúp các bạn tự tin đạt điểm cao trong kì thi này. Chúc các bạn thi tốt! | Flawed Beauty the problem with toughened glass On 2nd August a particularly hot day in the These crystals can exist in two forms a dense form town of Cirencester in the UK a large pane of called the alpha phase which is stable at high toughened glass in the roof of a shopping centre at temperatures and a less dense form called the beta Bishops Walk shattered without warning and fell phase which is stable at room temperatures. The high from its frame. When fragments were analysed by temperatures used in the toughening process convert experts at the giant glass manufacturer Pilkington all the crystals to the dense compact alpha form. But which had made the pane they found that minute the subsequent cooling is so rapid that the crystals crystals of nickel sulphide trapped inside the glass don t have time to change back to the beta phase. had almost certainly caused the failure. This leaves unstable alpha crystals in the glass primed like a coiled spring ready to revert to the beta phase without warning. The glass industry is aware of the issue says Brian Waldron chairman of the standards committee at the Glass and Glazing Federation a When this happens the crystals expand by up to 4 . British trade association and standards And if they are within the central tensile region of the development officer at Pilkington. But he insists that pane the stresses this unleashes can shatter the cases are few and far between. It s a very rare whole sheet. The time that elapses before failure phenomenon he says. occurs is unpredictable. It could happen just months after manufacture or decades later although if the glass is heated - by sunlight for example - the Others disagree. On average I see about one or process is speeded up. Ironically says Graham Dodd two buildings a month suffering from nickel sulphide of consulting engineers Arup in London the oldest related failures says Barrie Josie a consultant pane of toughened glass known to have failed due to engineer involved .