Ultrasonic characterization of modified Cr2O3 coatings by reflection coefficient spectroscopy

Li, Jicheng; Liu, Lin; Li, Ximeng; Li, Guang; Lei, M.K.

doi:10.1016/s1003-6326(09)60156-4

Cited by 10 publications

(4 citation statements)

References 18 publications

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“…The velocity in BL is much lower than that obtained for the dense materials with the same composition due to a large amount of pores and low elastic modulus from the BL. Similar results has been observed in the previous works [13][14] .…”

Section: Wstm Of Laser Ultrasonic Testingsupporting

confidence: 93%

“…Further, the values of SNR and RMSE (root mean square error) were calculated according to the Equations. (13) and (14) to evaluate the effect of noise reduction (Table 1). It was found that the best result was obtained using the rigsure method.…”

Section: Wstm Of Laser Ultrasonic Testingmentioning

confidence: 99%

“…It was found that the best result was obtained using the rigsure method. (14) where s(m) is the discrete result of original signal s(t) , s 0 (m) is the signal through filter, and m is the number of data. Then, the signals of TBC and substrate after WSTM were obtained in Figure 6.…”

Section: Wstm Of Laser Ultrasonic Testingmentioning

confidence: 99%

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Laser ultrasonic evaluation of bonding layer in thermal barrier coating

2015

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A noncontact laser ultrasonic method is provided for nondestructive characterization of bonding layer (BL) in thermal barrier coating (TBC). A physical mode of thin multi-layered structure is established for the case of received ultrasonic waveform consisting of reverberant overlapping echoes. Then, the transmission coefficient of the mode was derived in this work. Experiments have been performed on TBC specimens using the proposed method. The specimens are produced by electronic beam physical vapor deposition (EBPVD) method. A pulsed laser with width of 10 ns was used to generate ultrasonic while a two wave mixing (TWM) interferometer was employed to receive the ultrasonic signals. Wavelet soft-threshold method (WSTM) was introduce to improve the signal to noise ratio of laser ultrasonic testing TBC. The transmission coefficient spectrum of TBC was obtained to measure the longitudinal velocity of BL. Further, the numerical fitting method is used to determine the attenuation of BL. The proposed method is used to evaluate TBC after 1, 10 and 100 times, and the experimental results are in according with the SEM observations. This method is able to nondestructively characterize BL in TBC system, and is important to practical engineering application.

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Section: Wstm Of Laser Ultrasonic Testingsupporting

confidence: 93%

Section: Wstm Of Laser Ultrasonic Testingmentioning

confidence: 99%

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Laser ultrasonic evaluation of bonding layer in thermal barrier coating

2015

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“…The mechanical properties of the SiCp/Al composite was strongly related to the particledistribution as well as the interfacial bond strength between particles and matrix. This could be achieved by optimizing stirring parameters [7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Compared production behavior of borax and unborax premixed SiC reinforcement Al7Si-Mg-TiB alloys composites with semi-solid stir casting method

Haryono¹,

Sulardjaka²,

Nugroho³

2016

AIP Conference Proceedings

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Abstract. The present study was aimed to investigate the effect of borax additive on physical and mechanical properties of Al7Si-Mg-TiB with the reinforcement of silicon carbide. In this case, the different weight percentage from the reinforcement of SiC (10, 15, and 20% wt), and the borax additive (ratio 1:4) were homogenously added into the matrix by employing the semi-solid stir casting method at the temperature of 590°C. Al7Si-Mg-TiB melted in an electric resistance furnace at 800°C for 25 minutes and the holding time of 5 minutes; SiC was stirred with borax inside the chamber and heated at the temperature of 250°C for 25 minutes. Then, it melted by lowing the temperature into 590°C. The SiC-borax mixture was added into the electric resistance furnace, and automatically stirred by the stirrer at a constant speed (500 rpm for 3 minutes) in the composite A17Si-Mg-TiB. It melted when heated at 750°C for 17minutes,then, casting was performed on the prepared mould. The characterizations of Al7Si-Mg-TiB-SiC/borax were porosity, hardness, and microstructure on the Al7Si-Mg-TiB-SiC/ borax. The porosity of AMC tended to increase along with the increaseof the wt% SiC (1.4%-3.6%); however, borax additive underwent a decrease in porosity (0.14%-1.3%). Further, hardness tended to improve along with the increase of wt% SiC. The unboraxmixture had 79,6 HRB up to 94 HRB. Whereas, the borax additive mixture had 105,8 HRB up to 121 HRB.

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