Capital investment in an Instrument to Measure Particle Size Distribution (PSD)

我们建议采购一种专门的仪器来测量湿磨料浆液中的颗粒尺寸分布(PSD)。这将在优化STFC资助的两个项目中的金属精细抛光工艺方面发挥至关重要的作用，并大大提高英国满足英国和国际科学基地仪器要求的能力。这包括望远镜的光学和天文仪器，从微波到X射线，高功率激光系统，同步加速器反射镜和其他应用。第一个项目涉及抛光软材料，如铝，用于地面和空间天文学的反射镜和许多其他应用，这是一个非常困难的挑战。第二种是硬质材料，如复杂的模具和工具钢制的模具，用于工业大规模生产。化学镀镍的具体情况正好落在这两个项目之间--它是一种硬质金属涂层，有时作为一层薄层应用于铝镜，以便于抛光并提高耐用性，或者应用于模压模具，以复制用于X射线成像的薄壳镜。在开发这些工艺时，研磨抛光液有一个关键特性，我们目前没有关于它的信息：磨料颗粒的尺寸分布。有没有硬的最大尺寸，或者有几个更大的颗粒可以破坏表面？工作泥浆中的颗粒是聚集在一起(“凝聚”)还是破碎(“碎块”)，或者较大的颗粒是否沉淀下来？搅拌在实现颗粒均匀分布方面的作用是什么？重要的是，抛光液是否会被任何可能干扰抛光过程的东西污染(例如，降低表面粗糙度、造成划痕或凹痕等)。在任何材料的抛光过程中，无论是金属、玻璃还是微晶玻璃，PSD的变化还有另一个后果--它可以改变材料去除的速度，这被认为是工艺无法完全预测的原因之一。这反过来又会影响生产的时间、成本甚至风险。我们选择的工具既经济又多功能。它可用于两种方式：首先，当未稀释的泥浆通过我们的循环泥浆管理系统的回流管道时，它可以测量未稀释的泥浆。这将提供泥浆PSD的实时数据。其次，它可以与样品容器一起部署在工作台上-非常适合定期评估不再循环的专业浆液的小样本，但用于“全损”系统。鉴于精细抛光磨料的尺寸通常为2微米或更小，所选的仪器可以测量非常合适的颗粒尺寸范围-从大约10微米到大约1纳米(~10个原子！)。它承诺提供关于过程的丰富的基本数据，这些数据目前超出了我们和该领域许多其他工作人员的能力范围。这将为我们对流程如何运作的基本理解增加一个新的维度，帮助我们在竞争中保持领先地位，并使我们能够开发出更好、更具成本效益的流程。

We propose to procure a specialised instrument for measuring particle size distribution (PSD) in wet abrasive slurries. This will play a vital role in optimising processes for fine-polishing of metals in two STFC-funded projects, and materially enhance UK capability to meet instrumentation requirements of the British and International Science Base. This embraces optics for telescopes and instruments for astronomy from microwaves to X-rays, high-power laser systems, synchrotron mirrors and other applications besides.The first project involves the very difficult challenge of polishing soft materials such as aluminium, used for mirrors in ground-based and space astronomy and many other applications. The second concerns hard materials such as complex moulds and dies in tool-steels, used for industrial mass production. The specific case of 'electroless nickel' falls on the boundary between the projects - it is a hard metal coating, sometimes applied as a thin layer to aluminium mirrors for ease of polishing and increased durability, or on moulding dies to replicate the thin shell-mirrors used for X-ray imaging.In developing these processes, there is a key property of abrasive polishing slurries about which we currently have no information:- the distribution of the sizes of the abrasive particles. Is there a hard-maximum size, or are there a few larger particles that can damage surfaces? Do particles in working slurry clump together ('agglomerate'), or break up ('fragment'), or do larger particles settle out, and what is the role of agitation in achieving a uniform population of particles? And of great importance, does the slurry become contaminated with anything that could disturb the polishing process (e.g. degrade surface-roughness, cause scratches or digs, etc). There is another consequence of a change in PSD during polishing on any material be it metal, glass or glass-ceramic - it can change the rate of material removal, and this is believed to be one reason why processes are not fully predictable. This in turn impacts the time, cost and indeed risk of manufacture. The instrument we have selected is both economic and versatile. It can be used in two ways: first, it can measure undiluted slurries as they pass through the return pipe of our recirculating slurry management system. This will give real-time data on the slurry PSD. Second, it can be deployed on the bench with a sample container - very suitable for periodically assessing small samples of specialist slurries which are not recirculated, but used in a "total-loss" system. Given that fine polishing abrasives are typically 2 micron in size or less, the selected instrument can measure over a very suitable range of particle sizes - from about ten microns down to about a nanometre (~10 atoms!). It promises to provide a wealth of fundamental data on processes, which is currently beyond the reach of both ourselves and many other workers in the field. This will add a new dimension to our basic understanding of how processes operate, help us to stay ahead of the competition, and enable superior and cost-effective processes to be developed.