Fig. 1. Cross-section view of lining bonding structure

Fig. 2. Experimental device for laser ultrasonic monitoring of lining solidification

Fig. 3. Propagation path of ultrasonic wave in specimen. (a) Echo paths for the first nine times; (b) path of echo Ⅰ; (c) path of echo Ⅱ; (d) path of echo Ⅲ; (e) path of echo Ⅴ

Fig. 4. Propagation path of ultrasonic wave in bonding structure of metal plate lining. (a) Simulation cloud image of ultrasonic entering metal plate with thickness of 5 mm; (b) simulation cloud image of ultrasonic entering metal plate with thickness of 1.5 mm; (c) simulation cloud image of ultrasonic entering metal plate with thickness of 3 mm

Fig. 5. Detection point and A-scan signal in bonding structure of metal plate lining. (a) Detection point in bonding structure; (b) A-scan signal at detection point

Fig. 6. Simulated cloud images of the first nine echo arrival times. (a) Echo Ⅰ; (b) echo Ⅱ; (c) echo Ⅲ; (d) echo Ⅳ; (e) echo Ⅴ; (f) echo Ⅵ; (g) echo Ⅶ; (h) echo Ⅷ; (i) echo Ⅸ

Fig. 7. Laser ultrasonic monitoring of typical signal of lining solidification. (a) Time domain diagram of typical signal of aluminum lining bonding structure; (b) frequency domain diagram of typical signal of aluminum lining bonding structure; (c) time domain diagram of typical signal of steel plate lining bonding structure; (d) frequency domain diagram of typical signal of steel plate lining bonding structure

Fig. 8. Components of echo I arrival time

Fig. 9. Propagation principle of ultrasonic wave

Fig. 10. Variation curves of Z₂ with different variables. (a) Variation curve of Z₂ with A; (b) variation curve of k with D

Fig. 11. Echo I signal of lining in different states. (a) Echo Ⅰ signal of aluminum lining bonding structure; (b) echo Ⅰ signal of steel plate lining bonding structure

Fig. 12. Frequency domain diagram of echo Ⅰ signal in different states of lining. (a) Frequency domain diagram of echo Ⅰ signal of aluminum lining bonding structure; (b) frequency domain diagram of echo Ⅰ signal of steel plate lining bonding structure

Fig. 13. B-scan of echo I. (a) B-scan of echo I of aluminum lining bonding structure; (b) B-scan of echo I of steel plate lining bonding structure