A single screw extruder is a machine used to form a plastic product into the required shape. The machine heats the plastic raw material (e.g. PVC) to its melting point, after which it is pushed through a die that gives the material its shape. Single screw extruders are used to make plastic pipes used for trenchless construction projects.
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[ China Instrument Network Instrument Development ] On February 24, the Russian Science website reported that researchers from the National Research Institute of Technology at Moscow State University of Steel and Alloys have developed a new type of vibration sensor designed for structural health monitoring in buildings, bridges, and spacecraft. The sensor utilizes lead-free lithium niobate (LiNbO3) crystals, and the findings were published in the journal *Sensors*.
Compared to the zirconium titanate ceramics currently used in vibration sensors, lithium niobate crystals offer significantly better stability. This shift in material is expected to help manufacturers meet the EU’s regulations on phasing out lead-based components.
Irina Kubasov, a researcher at the Department of Semiconductor and Dielectric Materials, explained that these vibration sensors can be integrated into diagnostic systems for structures like buildings and bridges, helping detect dangerous vibrations early and allowing timely evacuations. They also hold potential for use in spacecraft and national security systems, offering comprehensive monitoring of territorial boundaries.
The sensor operates based on the piezoelectric effect—when vibrations occur, the piezoelectric element deforms and sends an alarm signal. However, traditional lead-based zirconium-titanate elements have proven problematic due to their toxicity and reduced sensitivity with temperature fluctuations. Researchers claim that all these issues have now been resolved with lithium niobate, which lacks the fine particles found in zirconium-titanate ceramics and maintains stable performance across a wide temperature range.
Although lithium niobate has been known since the mid-20th century and is widely used in laser optics, its application in vibration sensors has been limited due to its relatively weak piezoelectric properties—about ten times less sensitive than lead-based ceramics. However, scientists at Moscow State University of Steel and Alloys have successfully created a "dual-domain structure" within the lithium niobate crystal, significantly enhancing its sensitivity to external vibrations. This innovation could boost sensor sensitivity to as low as 10â»â¶ g and expand their operational temperature range considerably.
(Original title: Moscow State Steel and Iron Alloy Institute developed a new type of vibration sensor)