Microfinishing of Ultrafine Powders
In modern times, there is an increasing use of ultra-fine powders and nanopowders. Despite the many advantages these materials offer, they also come with a significant drawback. Due to their enormous surface area, they are much more susceptible to oxidation compared to their counterparts in rod, ingot, or disk form. When powders are properly packaged in high-quality PET bottles, sealed with membranes, and stored under argon atmosphere, they can maintain their stability for 10 to 15 years when stored upright. However, factors such as moisture, light exposure, horizontal storage, inferior containers, missing or leaking membranes, and similar conditions can reduce this shelf life. The end of the shelf life is typically indicated by small signs of corrosion, which cause the usually very fine particles to agglomerate into larger clumps. Once corrosion is noticed, immediate action is necessary, as the process spreads rapidly and continuously. Irreversibly corroded powder often appears graphite-like in appearance.
Packaging of Ultrafine Powders
Some powders are stored in glass ampoules that maintain a constant internal atmosphere for years. This type of packaging has both advantages and disadvantages. For industrial use, these containers are unsuitable, as glass ampoules cannot be opened without breaking the glass inside. The industry therefore prefers PET bottles. PET bottles are also more practical for air transport, as they are significantly lighter than glass ampoules. However, some powdersare used as financial assets due to their value sometimes exceeding that of gold. In such cases, glass ampoules are favored because they allow the powder to be stored virtually indefinitely in a sealed environment without the need for maintenance.
After a powder has been stored for ten years, an analysis test—including shape and size determination— should be conducted every two years thereafter. Using a scanning electron microscope, it can be quickly determined whether oxidation has begun. If oxidation is detected, prompt action is required to prevent further degradation.
The first step involves sieving the powder with an ultrasonic fine sieve to a specified particle size, typically ranging between 100 nanometers and 50 micrometers. In practice, this sieving process is usually repeated several times. Next, the particles are fragmented using an ultrasonic device, which reducesuheir size and rounds their shape. This fragmentation process is also repeated multiple times. The third step is tumbling the particles in an argon vacuum tumbler. Under a constant argon flow, the particles are mixed thoroughly. Argon attaches to each particle, forming a protective layer around them, which extends the powder’s shelf life by another 10 to 15 years. Finally, the processed powder is filled into high-quality PET bottles. The remaining approximately 10 cm of headspace at the top of the container is filled with argon gas—heavier than air—then sealed with a membrane to securely trap the argon inside. A safety cap protects the valuable contents in their new packaging. The bottles are then placed upright in their boxes inside an inlet to prevent tipping, and the boxes are resealed. All performed procedures are documented in a product report provided to the customer.
The Final Product
When it comes to the handling, processing, and packaging of high-quality powders, we don’t cut corners on the details. We use only branded bottles, caps, boxes, and inserts. Our machinery comes exclusively from reputable manufacturers. In the end, you receive a professionally and meticulously processed product, proudly made in Switzerland.
