Test method for materials outgassing performance in vacuum
1Key Takeaways
This standard specifies the test conditions, test equipment, sample preparation, test procedures, data processing, test reports, etc. for the volatility performance test of non-metallic materials for spacecraft under vacuum conditions. This standard is applicable to the ex situ test of the volatility performance of non…
2Expert Interpretation
In-depth analysis of the material volatility test method under vacuum conditions in the QJ 1558B-2016 standard, covering the three core indicators of total mass loss (TML), condensable volatile matter (CVCM) and water vapor resorption (WVR), and detailed interpretation of the test equipment requirements, sample preparation specifications and data processing methods.
Background of Standard Revision and Evolution of Key Technologies
As an important specification for vacuum performance testing of aerospace materials, QJ 1558B-2016 has made four major technical improvements compared to the 2012 version:
| Revision content | QJ 1558A-2012 | QJ 1558B-2016 | Technical significance |
|---|---|---|---|
| Cleanliness requirements | Not quantified | Clearly define Class 100,000 | Improve test environment control accuracy |
| Test unit structure | Horizontal symmetry axis | Longitudinal symmetry axis | Optimize molecular deposition path |
| Vacuum gauge calibration | Not specified | Detailed parameter requirements | Ensure the accuracy of vacuum measurement |
Analysis of core test indicators
Total mass loss (TML)
Calculation formula: TML = (SI - SF)/(SI - B - A) × 100%, where:
- SI: Initial mass of sample (including carrier)
- SF: Mass of sample after test
- B: Weight of sample boat
- A: Mass of carrier such as aluminum foil
Volatile Condensable Matter (CVCM)
Reflects the mass ratio of condensate on the collection plate at 25℃. The calculation formula is: CVCM = (CF - CI)/(SI - B - A) × 100%
Water Vapor Recovery (WVR)
Characterizes the hygroscopic characteristics of the material after the test. The calculation formula is: WVR = (SF' - SF)/(SI - B - A)
Key Test Equipment Specifications
| Equipment Components | Technical Requirements | Accuracy Indicators |
|---|---|---|
| Vacuum Test Chamber | 6+ Test Units, Oil-free Design | ≤7×10-3Pa |
| Temperature control system | Dual-channel independent temperature control | ±1℃ |
| Analytical balance | Micro weighing | 1μg sensitivity |
Standard implementation recommendations
- Sample preparation stage: The cutting size must be strictly controlled within the range of 1.5-3mm, and oil samples must be prevented from overflowing
- Blank control setting: 3 blank sample boat positions must be reserved, and the data will be invalid when the mass change is >50μg
- Non-standard test note: The reason for the heating temperature adjustment must be stated, and the result cannot be used for material screening
- Data cross validation: It is recommended that each group of samples be tested three times in parallel, and the difference in CVCM values should be <5%