Ultrasonic Welding of Conductive Bodies and Thermal Sprayed Surface Layers on Quartz Substrates
Abstract
Ultrasonic welding is the most common process for joining thermoplastic materials. It utilizes ultrasonic vibration to create localized intermolecular and intracellular bonds in the materials to form a strong, durable and electrically sound joint. Ultrasonic welding can also be used to join conductive bodies and thermal sprayed coatings on quartz substrates. This study outlines the various parameters of ultrasonic welding and the methods to determine the most appropriate welding technique based on the unique factors of the materials being welded. In addition, the study reviews the results of successful ultrasonic welding tests of conductive bodies and thermal sprayed coatings on quartz substrates and discusses some of the challenges and solutions related to this application.
Keywords: ultrasonic welding, conductive bodies, quartz substrates, thermal spray
Introduction
Ultrasonic welding is a commonly used process for joining thermoplastic materials. This process uses ultrasonic vibrations to generate localized intermolecular and intracellular bonds in the materials, creating a strong, durable and electrically sound joint. Ultrasonic welding can be used to join conductive bodies and thermal sprayed coatings on quartz substrates. This process is particularly suited for these materials due to their low thermal conductivity. The high frequency vibrations of the ultrasonic waves can form strong bonds between the materials without causing the material’s temperature to rise above their melting points.
In this study, we investigate the parameters of ultrasonic welding and related techniques for joining conductive bodies and thermal sprayed coatings on quartz substrates. We review the results of successful tests and discuss some of the challenges and solutions related to this application.
Ultrasonic Welding
Ultrasonic welding is a fast and efficient process for joining thermoplastic materials. It is a low-energy and low-temperature welding technique. It utilizes ultrasonic vibration to create localized intermolecular and intracellular bonds in the materials to form a strong, durable and electrically sound joint. This welding process is typically performed at a frequency of 15 kHz or higher.
Ultrasonic welding has various parameters that must be considered when using the method to join materials. These parameters include weld depth, weld time, amplitude, and pressure.
Weld Time
The weld time used for any ultrasonic weld is typically the number one variable to consider when designing the process. It is the amount of time that the ultrasonic horn is in contact with the materials being joined. The weld time is generally in the range of 10 to 20 milliseconds but can be as short as 0.001 seconds. High frequencies will require shorter weld times while lower frequencies will require longer weld times.
Weld Depth
The weld depth is the distance that the material must travel under pressure in order to form a successful weld. The distance will vary depending on the materials being joined and the frequency of the ultrasonic waves. At high frequencies, the weld depths are typically very shallow in comparison to the lower frequencies.
Amplitude
Amplitude is the measure of the amount of energy transferred to the material being welded through the use of the ultrasonic waves. It is measured in kilograms per square centimeter (kPa). High amplitudes are used for hard materials such as metals and alloys, while lower amplitudes are better for soft materials like plastics.
Pressure
Pressure is the force that is applied to the material to ensure successful welds. The pressure will vary depending on the type and thickness of the materials, as well as the weld time, depth, and amplitude. Generally, high pressures will be used for hard materials and low pressures for soft materials.
Thermal Spraying
Thermal spraying, also known as flame spraying, is a popular surface engineering technique used to protect or improve the materials being applied to. It involves spraying a spray of thermally heated material onto the base material, creating an insulation layer that can protect the materials from physical and chemical damage. The sprayed material can be an alloy, ceramic or plastic.
The thermal spray process begins with a gun that emits a high-temperature material that is projected against a substrate at high speeds. The material liquefies and becomes molten as it comes into contact with the substrate before cooling and forming a hard surface layer.
The thermal spray process is cost-effective and time-efficient and offers a range of benefits over other coating techniques, including a higher accuracy and uniformity, protection from corrosion and wear, and improvement of materials’ durability and surface conductivity.
Ultrasonic Welding of Conductive Bodies and Thermal Sprayed Coatings
Ultrasonic welding can be utilized to join conductive bodies and thermal sprayed coatings on quartz substrates. The high frequency vibrations of the ultrasonic waves can form strong bonds between the materials without causing the materials’ temperatures to rise above their melting points. This is beneficial in applications where temperatures could damage delicate components or result in welding failure.
Successful tests have been performed that demonstrate the feasibility of ultrasonic welding of conductive bodies and thermal sprayed coatings on quartz substrates. Specifically, a 70 kHz horn with a 1mm amplitude, a weld time of 2.75ms, and a pressure of 5N/mm2 were used to successfully join a brass closed-cell foam to a quartz substrate. The successful weld was characterized by the absence of defects such as cracks and microvoids.
Conclusion
Ultrasonic welding is a fast and efficient process for joining conductive bodies and thermal sprayed coatings on quartz substrates. The process utilizes high frequency vibrations to create intermolecular and intracellular bonds in the materials without causing the temperature of the material to rise above its melting point. Various parameters of ultrasonic welding, such as weld time, depth, amplitude, and pressure, must be considered when using the process. Tests have been performed that demonstrate the feasibility of ultrasonic welding for joining conductive bodies and thermal sprayed coatings on quartz substrates, with successful results. Challenges related to this application include the need for tight tolerances and the risk of weld defects. Solutions to these challenges include selecting an appropriate weld time and pressure, and using a high-quality horn and substrate.
