The characterization of high-temperature anti-coking performance of phenyl silicone oil needs to be combined with thermal stability test, coking amount analysis, physical property monitoring and microstructure characterization, and refer to industry technical standards and equipment specifications. The following is a specific analysis:

1. Characterization method
Thermal stability test
Constant temperature thermogravimetric analysis (TGA): In a nitrogen or air atmosphere, heat to the target temperature (such as 300℃-350℃) at a constant heating rate (such as 10℃/min), record the mass loss curve, and evaluate thermal stability by thermal decomposition temperature (Td) and residual mass percentage.
Accelerated aging experiment: Continuously heat at high temperature (such as 150℃-300℃) for hundreds of hours, regularly detect mass changes, viscosity growth rate and coking product generation to simulate anti-coking performance under long-term use conditions.
Coking amount analysis
Mass loss method: Calculate the coking amount by the mass difference before and after high temperature treatment, suitable for rapid laboratory evaluation.
Solvent extraction method: Use organic solvent (such as toluene) to extract the uncoked oil, and the residue is the coke, which can accurately measure the amount of coking.
Image analysis method: Observe the samples after high temperature treatment by scanning electron microscope (SEM) or optical microscope, and quantify the area or volume proportion of coke by combining image processing software.
Physical property monitoring
Viscosity change: Regularly measure the kinematic viscosity of the samples after high temperature treatment (such as 25℃ or 100℃), and the viscosity growth rate reflects the degree of obstruction of the coke to the movement of molecular chains.
Acid value determination: The content of oxidation products (such as carboxylic acids) is detected by acid-base titration. The increase in acid value indicates that thermal oxidation coking is intensified.
Microstructure characterization
Infrared spectroscopy (FTIR): Analyze the changes in characteristic functional groups (such as Si-O-Si, Si-Ph, C=O) in the samples before and after high temperature treatment to identify the oxidation products and coke structures.
Nuclear magnetic resonance (NMR): Analyze the changes in molecular chain structure through hydrogen spectrum (¹H NMR) or carbon spectrum (¹³C NMR), and quantitatively evaluate the degree of crosslinking and phenyl content loss.

2. Technical standards and specifications
Appearance and impurity control
The sample should be a colorless to light yellow transparent liquid with no visible suspended matter and sediment (refer to Q/SH3031 0147-2019 standard).
The mass fraction of mechanical impurities should be lower than the detection limit (such as 0.01%) to avoid impurity catalytic coking.
Thermal stability index
The open flash point is not less than 300℃ (GB/T 3536), and the freezing point is not higher than -20℃ (GB/T 510), ensuring high temperature safety and low temperature fluidity.
The thermal decomposition temperature (Td) should be higher than 300℃, and the residual mass percentage should be less than 10% (TGA test).
Coking limit
After the accelerated aging experiment, the coking amount should be less than 5% (mass fraction), and the viscosity growth rate should not exceed 20% (25℃ kinematic viscosity).
The acid value increment should be less than 0.05 mgKOH/g (GB/T 264), indicating that the degree of oxidation coking is controllable.
Test equipment and conditions
TGA test requires a high-precision thermal analyzer (such as TA Instruments Q500), a heating rate of 10℃/min, and a nitrogen atmosphere (flow rate 50 mL/min).
Viscosity measurement uses a rotational viscometer (such as Brookfield DV-II+) in accordance with GB/T 265 standard.
Infrared spectroscopy analysis uses a Fourier transform infrared spectrometer (such as Thermo Fisher Nicolet iS5) with a resolution of 4 cm⁻¹ and 32 scans.