A Comparative Study on the Mathematic Models for the Ignition of Titanium Alloy in Oxygen-Enriched Environment
Vladimir A. Skripnyak
Round 1
Reviewer 1 Report
The manuscript presents the results of original experimental and theoretical investigations of the effect of size, oxygen concentration and oxygen pressure on the ignition temperature and critical oxygen pressure for the TC17 titanium alloy. An ignition model is proposed to describe the critical ignition conditions for a solid titanium body using the Semenov and Frank-Kamenetsky ignition criteria. The results obtained by the authors indicate that the critical oxygen pressure for ignition of a bulk sample of TC17 alloy increases with increasing its size, which agrees well with the Frank-Kamenetsky model description of ignition.
The presented results are of interest for a wide range of specialists carrying out researches in the field of modern and advanced technologies for welding of titanium alloys, chemical technologies using equipment of alpha and pseudo-alpha titanium alloys, as well as those working in the field of titanium alloys processing.
The quality of the manuscript should be improved.
1) Marks and manufacturers of experimental equipment should be specified in subsection 3.2. There is no information in the text about the method and instruments for controlling the pressure in the combustion chamber. There is no information about the method of monitoring the content of oxygen and nitrogen in the gas mixture under conditions of changing temperature.
2) It is known that infrared thermography and infrared thermometry determines the apparent on the surface of an object. Surface reflection coefficients can distort information about the temperature of an object. Therefore, a methodology for estimating the surface temperature of samples should be added to the article. An accuracy of ± 5 K should be justified for temperature measurements in the range from 900 K to 1300 K.
3) The heating rate in experiments and the temporal resolution in recording the ignition process should be clarified. The influence of the formation of surface titanium oxides on the formation of the beta phase in TC17 alloy should be explained. This information is needed in order to interpret the observed change in the slope of the temperature versus O2 pressure line in Figure 5(a) at temperatures above 1000 K.
4) It is necessary to supplement the manuscript with information about the structural parameters of the used titanium alloy samples (parameters of grain size distribution, phase composition of the alloy). It is known that oxygen diffusion rate can increase by decimal orders in titanium alloys in nanostructured and ultrafine-grained structural state.
5) In Figure 3(b), it is necessary to correct "Semonev" to "Semenov".
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Reviewer 2 Report
This study attempts to introduce two mathematic models (F-K model and S model) for the prediction of ignition temperature at different size (1 mm ~ 12 mm) and oxygen pressure of TC17 alloy. The manuscript is scientifically sound and the experimental design is appropriate to compare the two mathematic models. It can be published but after the minor revision.
1. It is suggested that rewrite the “Model” to “Mathematic models” at Line 94.
2. Check the Line 103-107, where the sentences are not clearly constructed.
3. It is recommended that rewrite the bold sentences at Line 113-115.
4. It is recommended that replace the “c(m)” to “c(m) = lm” in Table 2 at Line 218.
5. It is recommended that omit “geometry” in “Effect of geometry size on critical oxygen pressure” at Line 220.
6. Please use capital “Effect” at Line 256.
7. How about adding the mathematic model type (F-K model or Semenov model) for each parameters in Table 3 at Line 276?
8. Please check the format at Line 334-336.
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Author Response
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