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千克基准是质量的计量基准,它的质量必须是非常稳定的,为此要对千克基准作精心的维护,避免出现产生质量变化的事故。引起质量变化的原因有:表面沾染灰尘,表面层材料受潮湿空气或有害气体的轻微腐蚀;基准底面的磨损;基准圆柱面受夹钳的划伤等等。为了避免发生这些情况,国际计量局把国际千克装在带有三个玻璃罩,且其中最外层的一个可以抽成半真空的、可防止污染的容器里(图5-6)。为了防止在存放时,由于温度的影响使承受基准的支承台因膨胀或收缩所产生对千克基准
The kilogram basis is a measure of quality and its quality must be very stable. Careful maintenance of the kilogram benchmarks is therefore necessary to avoid accidents that result in quality changes. Causes of quality changes include: surface contamination with dust, the surface layer of material by the damp air or harmful gas minor corrosion; wear the bottom of the benchmark; the reference cylinder by the clamp scratches and so on. To avoid these situations, the International Bureau of Weights (IJM) installed an international kilogram in a three-glass, one-outer, semi-vacuum containment container designed to prevent contamination (Figure 5-6). In order to prevent the storage due to the influence of the temperature to support the benchmark support due to expansion or contraction of the kilogram benchmark