Definition
The Wire Rod Scraper Heated Vacuum Adsorption Coating Machine is a laboratory coating equipment used to prepare uniform, controllable thickness coatings on the surface of a flat substrate. It realizes precise control of the coating process by combining the three functions of wire rod scraping, substrate heating and vacuum adsorption fixation, and is widely used in sample preparation and process research in materials science, electronics, new energy, packaging and printing and other fields.
How it works:
The working principle of the device is based on three synergistic subsystems. First, the vacuum adsorption system generates negative pressure through the micropores of the worktop, flattening flexible or rigid substrates (such as films, metal foils, glass plates) to the countertop, eliminating wrinkles or displacements. Secondly, the built-in heating system evenly heats the adsorbed substrate, and the temperature is usually adjustable to change the rheological properties of the coating solution. Finally, the operator uses a precision wire rod scraper (also known as a Meyer rod) to scrape over the surface of the substrate at a constant speed and pressure, scraping away excess coating fluid and forming a wet film of a specific thickness in the substrate grooves. The thickness of the wet film is mainly determined by the diameter of the wire wound on the wire rod (i.e., the wire diameter), and its theoretical dry film thickness can be estimated by the formula.
Dry film thickness ≈ wire rod wire diameter × Percentage of coating liquid-solid content × Correction factor
The correction coefficient is related to the leveling of the coating solution, solvent volatilization and substrate properties.
Measurement and calibration methods
The measurement of coating quality mainly focuses on coating uniformity and thickness. The thickness of the wet film can be controlled theoretically by the specification of the wire rod, while the confirmation of the thickness of the dry film requires the use of professional instruments. Common methods include using a micrometer to measure the thickness difference between the substrate before and after coating, or using a non-contact thickness gage (such as a laser displacement sensor). Coating uniformity can be analyzed by observing interference fringes with the naked eye or by using optical microscopes and profilers. The calibration of the equipment focuses on the flatness of the temperature control system and the coating platform. The temperature is multi-point verified by a calibrated surface thermometer or thermal imager. The flatness of the platform needs to be tested using a level and a thickness gauge to ensure that the surface of the substrate is not deformed during vacuum adsorption.
Influencing factors
The quality of the coating is affected by multiple factors. In terms of coating fluid parameters, viscosity, solid content, solvent volatilization rate and leveling directly affect the uniformity and final thickness of the coating. In the operating parameters, scraping speed is the key; Too fast speed may lead to discontinuity of the wet film, and too slow is easy to cause sagging. The choice of wire rod, including wire diameter, winding method and material, directly determines the thickness range of the wet film. Environmental conditions such as ambient temperature and humidity can affect solvent volatilization and coating fluid fluidity. The equipment itself factors include the uniformity and stability of the heating temperature, the uniformity of vacuum adsorption and the absolute level of the coating platform.
Applications:
This equipment is suitable for a wide range of applications where precision thin film samples need to be prepared. In the field of new energy, it is used to prepare samples of lithium-ion battery electrode coatings, fuel cell catalytic layers, or photovoltaic functional layers. In the field of electronic materials, it is used to coat conductive silver pastes, insulating media or optical films. In the packaging and printing sector, it is used to develop barrier coatings, inks or adhesives. In the research of basic materials, it is a common tool for the preparation of polymer films, nanocomposite coatings and various functional coatings.
Selection considerations
When selecting the model, it is necessary to comprehensively consider the experimental requirements and equipment performance. Core parameters include coating width, which determines the maximum sample size; The heating temperature range and uniformity need to match the process window of the material used; The size and adsorption force of the vacuum adsorption zone should ensure that the substrate used is firm and flat. The wire rod scraper system needs to look at the specification range, material (such as stainless steel), and fixed stability and parallelism of the wire rod. In terms of equipment control, programmable scraping speeds and heating controls help improve process repeatability. In addition, the material structure of the equipment should be chemically resistant, easy to clean, and the overall design should meet relevant safety standards.