1.How to quickly assess and monitor the process on-site?
Visual and tactile inspection (basic)
Method: Observe the surface under good lighting for oil spots, dust, rust, fingerprints, etc. Touch the surface with gloves to feel for any greasiness.
Water film rupture test
Method: Spray or apply distilled water or a specified solution to the surface of the steel strip, and observe the continuity and rupture time of the water film.
Tape/Film Test Method
Method: Apply a special pressure-sensitive adhesive tape or clean PET film tightly to the surface of the steel roll, then peel it off and observe the contaminant particles adhering to the tape/film.
2.What is the gravimetric method used to measure?
Method: Clean a sample area (usually 1 m²) with a specified solvent, evaporate the eluent, and weigh the residue.
Unit: mg/m² (total residue weight). This is the most direct and classic quantitative indicator.
Advantages: Objective and accurate data; serves as a calibration benchmark for other methods.
Disadvantages: Cumbersome and time-consuming operation; cannot distinguish contaminant components.
3.What is spectral analysis used to measure?
Fourier Transform Infrared Spectroscopy (FT-IR):
Principle: Analyzes the characteristic absorption peaks of functional groups in organic components of contaminants (such as rolling oil, esters, and rust inhibitors).
Applications: Identifies the type of contaminant (what kind of oil it is) and performs semi-quantitative analysis. Commonly used for failure analysis and contaminant source tracing.
4.What are the principles and procedures of hydrocarbon determination?
Method: An infrared carbon-sulfur analyzer or a total organic carbon analyzer is typically used.
Principle: The sample is burned at high temperature in an oxygen stream, converting carbon in the pollutants into CO₂. The residual carbon content is then inferred by detecting the CO₂ content.
5.What is the contact angle measurement method?
Method: The static contact angle of a water droplet on a steel strip surface was measured using a contact angle meter.
Principle: A larger contact angle indicates stronger surface hydrophobicity and a higher concentration of organic contaminants.
Advantages: Rapid, non-destructive, and can be performed online.
Disadvantages: Highly affected by surface roughness and microstructure; comparison with a standard sample is required.