Разные технологии определения размера частиц дают разные результаты измерения, но что из них Истина?
Наиболее распространенными методами определения размера частиц являются следующие: динамический анализ зображений (ДАИ), статическое лазерное рассеивание света (СЛРС, или лазерная дифракция) и ситовой анализ. В данной публикации описаны преимущества и недостатки каждого из методов, их сравнение на примерах различного использования.
Advances in Powder Metallurgy production technologies are generating an increased demand for tailored and tightly controlled powders with distinctive properties. The control of particle size distribution, as well as particle shape, is an important step in the quality control process. In this article we compare the three most commonly used methods for powder characterisation and highlights the pros and cons of each process.
With an estimated 1.4 billion cups of coffee consumed worldwide every day, there is a great and ever increasing demand for coffee beans in the global market. The taste of coffee is influenced by the roasting of the beans, their grinding degree and the method and quality of the preparation. Different types of preparation by brewing and filtering (e.g. espresso machine, filter coffee or mocca) require different grinding degrees of the coffee powder to obtain an aromatic result. When roasted beans are ground to powder, the determination of the particle size is a critical aspect because the particle size influences the brewing and filtering properties and thus the taste and salubriousness of the coffee.
Sieve analysis and laser diffraction are long established methods for the determination of particle size distributions. Dynamic Image Analysis (DIA) is another particle analysis technology to measure particles > 1 micron which has numerous advantages over these methods.
Retsch Technology’s particle analyzers CAMSIZER and CAMSIZER XT, which are based on DIA technology, evaluate images of the particles which provide considerably more information on the particles than, for example, a light scattering pattern produced by a laser diffraction particle analyzer. These only allow for an indirect measurement of the particle size. The determination of parameters such as the length, width, or sphericity of particles is only possible by using image analysis.
Traditionally, particle size distribution analysis of pharmaceutical powders and granules is carried out by sieve analysis, microscopy or with laser diffraction. These methods are established in the pharmacopoeia and used routinely in pharmaceutical laboratories all over the world. With the introduction of Dynamic Image Analysis (DIA) as an alternative method, it is now possible to measure particle sizes >1 micron of powders, granules, pellets and suspensions as well as particle shape. A number of trials clearly demonstrate the advantages of DIA compared to the established particle sizing methods.
The CAMSIZER XT has been successfully installed at building material plants around the world replacing sieve analysis by providing quick, reliable high resolution results while still matching historic sieve data. The typical measurement time varies between 1 to 3 min depending on the desired measuring statistics. Reported result parameters include smallest diameter, length, mean diameter, aspect ratio, symmetry, sphericity, and convexity.
Quality control of solder powders with the CAMSIZER XT - solder pastes are used in the electronics industry for reflow-soldering of SMD (surface mounted devices) components on printed circuit board (PCB) assemblies. The solder paste is printed on the contact pads and the components are mounted on these pads. The paste attaches the components on the PCB until the PCB is heated in an oven where the solder paste melts. The melt connects the electronic components (resistors, transistors, ICs, EPROMS, etc.) and the contact pads of the PCB providing the electric contact and mechanical fixture after cooling and solidification. An essential component of solder paste, beside the flux, is the solder powder.
Sieve analysis according to ICUMSA Method GS2/9-37 is the standard for particle sizing of crystal sugar. Officially, all labs follow these guidelines, and comparable results should be seen in round robin tests. On a closer look however, each lab follows procedures that deviate slightly from those outlined in the ICUMSA Method. As a result, the size distributions measured by different labs vary remarkably. In this article we will discuss the typical deviations that can be found in the daily operation, and propose a new analysis method which provides more reproducible and reliable results.
Laser diffraction is the most frequently used measurement technique for the analysis of particle size distributions in the range 1 micron to 1 mm in the context of quality control. Modern laser diffraction systems offer some convincing advantages such as short measurement times, easy operation and reproducible analysis results. However, they also have various disadvantages: Even if the instruments have been calibrated and validated, an absolute particle size measurement is not possible. Various round robin tests have shown that the analysis results depend strongly on the type of instrument and even on the particular model and software version.
The quality control of fine powders can be substantially improved with the new CAMSIZER XT: More precise and faster analysis of particle size and particle shape helps to improve the product quality, reduce rejects and save costs.
Области применения (10)
Абразивы это зернистые материалы, обладающие высокой твердостью и используемые для обработки поверхности различных материалов. Эти материалы, как правило, включены в шлифовальные инструменты, либо на поверхности некоторых носителей (например, бумага) или в керамически-скрепленных абразивных телах (например, отрезные круги)....
Благодаря модульной конструкции анализатор CAMSIZER XT, обнаруживает оба типа зерен макро и микрозерна. Модуль сухого диспергирования частиц Х-Dry с картриджем X-Fall идеально подходит для измерения макрозерен.
The building materials industry uses naturally occurring substances such as various minerals like limestone, clay, sand, glass (SiO2) or wood as well as synthetic polymers and multiple combinations of both (composites). No matter which type of building material, the particle size and shape of the raw materials influence the physical properties of the end product, and therefore need to be analyzed as part of the quality control process.
Woodfibers are a 100% renewable organic material which is used for many different applications, including for example construction materials, animal bedding pellets, and biomass for energy generation. For all these applications, wood is shredded into fine chips or flakes, or finely ground (sawdust). The size and shape of the particles is not only important for the homogeneity and strength of chipboards, as well as their production process parameters, but for example also for the gasification of wood as biofuel in engines. For the latter process, the surface area of the pulverised material, for example, will strongly influence the pyrolysis process.
The size and shape of the cellulose fibers are important for example for the texture of the final paper surface, but also for inherent properties of the final product like the tensile strength as well as for production parameters. Thus the quality control of the raw fiber material is an important step, for example for the production of special papers for banknotes. Traditionally, the fibers are analysed under a microscope or with laser particle sizers. The first method provides an overview over the shape of the particles, but it is a tedious, time consuming process which does not allow to measure a representative large number of fibers. The second method is fast and analyses many particles simultaneously, but it does not allow for shape analysis. Thus, both methods are not optimal. The CAMSIZER XT provides both: analysis of a high number of particles in a short time, and information about the shape of the fibers.
The size range of the metal powders varies from a few μm to mm size, depending on the applications. Different processes are used for the production of the powders, including grinding and various atomization processes (gas, water, spinning disc). Most commonly the wide size range of the initial production step is narrowed down by sieving or sifting techniques to final products with narrow size ranges.
The CAMSIZER XT can analyze the foodstuffs which typically come in many different forms of appearance such as powders, crystals, granulates or suspensions. Particle size of both raw materials and finished products affect taste, solubility, exctraction behavior, mouth feel and many other physical properties. The material is often agglomerated, oily or sticky, so proper dispersion is a big challenge. Air jet sieving or laser diffraction are commonly used mehods, but they suffer from bad resolution and high labour input (sieving) or limited data significance or sensitivity (laser diffraction).
The term “Additive Manufacturing” describes a process where digital 3D design data, typically generated by CAD, are used to build a component layer by layer by depositing material. A number of manufacturers offer 3D printers or systems for Additive Manufacturing based on a variety of technologies and materials.
The basis for most of the above-mentioned processes is a powder bed on which material is sequentially deposited. Depending on the desired specifications of the 3D components, different types of powders are employed in the printing process. The particle size distribution and shape of the powders is a critical parameter for the operating conditions of the printer and also for the properties of the final product.
The CAMSIZER XT may be used for the size and shape analysis of graphite, powdered or crushed coal and coke, activated carbon even industrial diamonds which are used as abrasives. If the material is a fine powder or does not flow freely due to high dust content, the X-Jet module can be used. For coarser, dust-free material samples the X-Fall is an option.
Any material used for construction purposes can be called building material. They are used in multiple facets of construction including carpentry, roofing, structural reinforcement, insulation, and plumbing. The particle size and shape of the raw materials used influence quality and performance, and therefore require analysis to quantify these physical properties. This application note describes how the CAMSIZER XT has been successfully implemented to determine the size and shape of various building materials.