3-D-printed smart screw: functionalization during additive fabrication

Integrating sensors into machine parts is a necessary step for the development of smart or intelligent components. Sensors integrated into materials such as concrete, fiber compounds, or metals are already used to measure strain, temperature, or corrosion. The integration is mostly done during fabrication, where the sensor is recast in the material during processing. However, approaches to integrate sensors into parts fabricated by additive manufacturing are still rarely found. Especially in the case of rapid prototyping, additive techniques are already substituting the machining of parts using classical technologies like cutting, drilling and milling. To characterize such 3-D-printed machine parts the direct integration of sensing elements is the next logical step. This can be done in multi-material printing by using insulating, magnetic, and conductive materials. In the case of single material printing, our idea is to integrate a sensing element during the printing process itself. As proof-of-concept, we present the functionalization of 3-D-printed screws. Strain gauges screen-printed on a 6 µm thick foil are interposed into the 3-D part during microstereolithography printing. We measure the torsional strain in the screw head to calculate the prestressing force in screws made from different plastic materials. We also analyze the defect effect by comparing it to screws without integrated elements.

Coil Type Ultrasonic Motor for Vascular Endoscope

IVUS (Intravascular Ultrasound) is a useful medical device to observe the thrombus in blood vessels, and such a micro motor less than 1.0mm in outer diameter is desired to apply IVUS in narrow brain vessels. In our previous works, ultrasonic motor consisting of a wire coil type stator, a waveguide, a cylindrical rotor, an ultrasonic vibrator has been developed. This motor is rather easy to miniaturize because of its simple structure. However, this motor behavior is unstable rotate. To improve these problems, a foil type stator has been applied in stead of a wire coiled stator. An ultrasonic motor with 0.05mm thick foil type stator was manufactured and tested their performances. It was able to verify that this ultrasonic motor with a foil type stator has the right quality. So, simplified IVUS system using ultrasonic motor with a foil type stator was manufactured and tested their fundamental performances. In order to expand development of new application, ultrasonic motor with a shortened waveguide and ultrasonic motor integrated driving unit with a stator was developed.

Preparation and Properties of a Custom-Designed Nickel-Based Amorphous Brazing Foil

The custom-designed amorphous brazing filler metals in foil form has been developed for application in brazing stainless steel 0Cr18Ni9. The new alloys contains 10.5wt% chromium, 5.4wt% silicon, 1.5wt% boron, 3wt% cobalt and nickel as the balance. The melting range is within 971°C1070°C. The alloy exhibits good melting characteristics and wetting behavior. With a 25μm thick foil, the joint is free of brittle central eutectic phases inside the joint via diffusion of the alloying elements into adjoining base metal and results on a high mechanical joint strength.

Evaluation of Alumina-Forming Austenitic Foil for Advanced Recuperators

A corrosion- and creep-resistant austenitic stainless steel has been developed for advanced recuperator applications. By optimizing the Al and Cr contents, the alloy is fully austenitic for creep strength while allowing the formation of a chemically stable external alumina scale at temperatures up to 900°C. An alumina scale eliminates long-term problems with the formation of volatile Cr oxy-hydroxides in the presence of water vapor in exhaust gas. As a first step in producing foil for primary surface recuperators, three commercially cast heats have been rolled to ∼100 μm thick foil in the laboratory to evaluate performance in creep and oxidation testing. Results from initial creep testing are presented at 675°C and 750°C, showing excellent creep strength compared with other candidate foil materials. Laboratory exposures in humid air at 650–800°C have shown acceptable oxidation resistance. A similar oxidation behavior was observed for sheet specimens of these alloys exposed in a modified 65 kW microturbine for 2871 h. One composition that showed superior creep and oxidation resistance has been selected for the preparation of a commercial batch of foil.

Evaluation of Commercial Alumina-Forming Austenitic Foil for Advanced Recuperators

A corrosion- and creep-resistant austenitic stainless steel has been developed for advanced recuperator applications. This fully austenitic alloy is optimized for creep strength while allowing the formation of a chemically-stable external alumina scale at temperatures up to 900°C. An alumina scale eliminates long-term problems with the formation of volatile Cr oxy-hydroxides in the presence of water vapor in exhaust gas. The first batch of commercially fabricated foil was produced with a composition selected from prior laboratory creep and oxidation results. The results for ∼80 and ∼105μm thick foil are compared to the prior laboratory-fabricated foils and other commercial candidates. Results from initial creep testing at 750°C show comparable creep strength to other commercial Fe-base foil candidates. Laboratory exposures in humid air at 650°–800°C have shown excellent oxidation resistance for this composition. Similar oxidation resistance was observed for sheet specimens of the first set of alloys exposed in a modified 65kW microturbine for up to 6,000h.

Evaluation of Alumina-Forming Austenitic Foil for Advanced Recuperators

A corrosion- and creep-resistant austenitic stainless steel has been developed for advanced recuperator applications. By optimizing the Al and Cr contents, the alloy is fully austenitic for creep strength while allowing the formation of a chemically-stable external alumina scale at temperatures up to 900°C. An alumina scale eliminates long-term problems with the formation of volatile Cr oxy-hydroxides in the presence of water vapor in exhaust gas. As a first step in producing foil for primary surface recuperators, three commercially cast heats have been rolled to ∼100μm thick foil in the laboratory to evaluate performance in creep and oxidation testing. Results from initial creep testing are presented at 675° and 750°C showing excellent creep strength compared to other candidate foil materials. Laboratory exposures in humid air at 650°-800°C have shown acceptable oxidation resistance. Similar oxidation behavior was observed for sheet specimens of these alloys exposed in a modified 65kW microturbine for 2,871h. One composition that showed superior creep and oxidation resistance has been selected for preparation of a commercial batch of foil.