WO2022190123A1

WO2022190123A1 - An apparatus and a method to analyze the degradation of the thermo-chemical properties in a material

Info

Publication number: WO2022190123A1
Application number: PCT/IN2022/050202
Authority: WO
Inventors: Babasaheb Neelkanth Kalyani; Deepak Foujdar GHULE; Abhishek S. KASHINATH; Karthik C. PADMASHALI; Rajkumar P. SINGH
Original assignee: Bharat Forge Limited
Priority date: 2021-03-08
Filing date: 2022-03-08
Publication date: 2022-09-15

Abstract

The present invention relates to an apparatus to determine degradation in properties of material used to manufacture a component which is subjected to thermal and chemical loads during its working. It comprises: gas chamber (114); a first inlet (104) for transmitting steam; a second inlet (106) for transmitting calibration gas; both inlets connected to a mixer (110) in which the calibration gas and steam are mixed to form a mixture; said gas chamber (114) to receive the mixture via a connecting pipe (128), the connecting pipe has a first valve (118) to control flow of the mixture; a second valve (108) for purging nitrogen gas; a flame arrestor (112); a specimen holder (120) to hold specimen (122); a window (116) in line with the specimen holder (120); a laser source (102) to emit a laser pulse through the window (116) to generates thermal shocks on the specimen (122).

Description

AN APPARATUS AND A METHOD TO ANALYZE THE DEGRADATION OF THE THERMO-CHEMICAL PROPERTIES IN A MATERIAL

FIELD OF INVENTION

The present invention relates to an apparatus and a method to analyze the physical, thermal and chemical properties of a material, which is used to manufacture a component, which is subjected to thermal and chemical loads or shocks during its working. More particularly, the invention relates to an apparatus and a method to determine the degradation in the properties of the material used to manufacture the component (subjected to thermal and chemical loads during its working) when in virgin condition or coated with a protective layer, under pre-determined conditions.

DESCRIPTION TO THE RELATED ART

There are several cases where a certain product or system has to face significant thermal and/or chemical loadings during its working. Such type of products or systems fails under these thermal or chemical loads through mechanisms like thermal degradation, chemical degradation or mechanical degradation. These mechanisms are explained with the help of following example.

A propulsion/thrust tube/vessels of jet engine or any component facing firing conditions, when in operation is subjected to numerous undesired thermal effects, chemical effects, metallurgical effects and mechanical effects which all contribute to the shortening of the life of the tube/vessel. More particularly, the internal surface of the tube gets more affected and starts degrading with numerous effects mentioned above. As the surface of the propulsion tube is subjected to passage of hot gases at high velocity, erosion of the internal surface of the tube occurs. These hot gases have different chemical composition and along with erosion these gases also lead to thermal attacks/loads and chemical attack on the material from which the propulsion/thrust tubes/vessels are made. This leads to thermal, mechanical and chemical degradation of the material.

The combination of erosion, thermal degradation and chemical degradation results in the formation of pits in the internal tube surface and wearing of accurately machined parts in a short duration of time. This is especially pronounced in sections that have been subjected to electrochemical corrosion resulting from deposition of pyrolysis products such as sulfides, nitrates and sulfates in small cracks in the tube from which they are not easily removed by cleaning. In addition, driving band debris builds up on the tube resulting in further degradation of propulsion/thrust tube/vessel performance. The reclamation of the tube components is a difficult and costly process, thus it is desirable to limit degradation of the surface due to erosion, thermal loads and chemical attacks, if possible.

The combustion of the gas in the propulsion system results in a flow of pressurized gas having high temperature and a high kinetic energy which continuously impulse on the internal surface of the propulsion tube. Due to this impulse action on the internal surface included, among the deleterious thermal effects resulting from the exposure to these high thermal energy pulses, are melting, phase transformations, and surface cracking (heat checking).

It is well established that higher the surface temperature of the internal surface of the tube during passing of hot gases, more the erosion will take place. Also, hot gases may overheat the tube, thereby subjecting to increased frictional wear and in extreme cases the tube may soften where there is permanent deformation or warping. Propulsion/thrust tube’s life is greatly reduced under such conditions. It is therefore apparent that significantly reducing the heating and erosion of the tube would improve the service life of the propulsion/thrust tube/vessel.

For any of the application similar to the propulsion/thrust tube given above, the material, which is used to make the component or system which faces these thermal, chemical or erosion degradation mechanisms, needs to be able to sustain these loads. The intrinsic properties (i.e. degradation resistance) of this material/materials dictate the life of these products or systems. There are several ways by which the life of such system or product

(like a propulsion/thrust tube) can be increases or optimized. There are known prior arts wherein the surface of the product or system, which faces these degradation mechanisms, is coated with chrome or some other hard refractory material. Another approach involves the use of additive wear liners such as dimethylsilicone, talc-wax, or titanium dioxide-wax etc. These additives coat the relevant surface of the product or system and thereby reduce heat transfer and chemical attack on this surface.

In order to increase or optimize the life of these products or systems, it is of great importance to select the right material or coating or manufacturing route which gives the product or system the required degradation resistance. The known techniques have some advantages as well as some shortcomings which need to be evaluated and compared with each other. For this, it becomes necessary to test the performance of the material or coating or manufacturing process when it faces the thermal, chemical or erosive degradation mechanisms.

One of the methods to test is to create the real working environment in a test setup by generating and passing the actual hot gases over the relevant surface of the product or system. But, the disadvantages connected with such type of testing are as follows: 1. This type of testing apparatus/system is very big in size and hence, cumbersome.

2. This type of testing apparatus/system is very costly to make and operate which increases the overall development cost of the solution for life improvement. 3. The testing time required in such apparatus and method is also long which increases the overall development timelines.

4. This type of testing apparatus needs lot of safety measures.

5. Further even with so much investment in time, effort and resources, the results are still not as accurate as desired.

It is therefore required to develop an apparatus for an experiment to study and analyze the behavior of the material, coating or manufacturing method in a pre-determined condition wherein the relevant surface with chemical environment similar to that found in working condition and a high temperature and high pulse energy of the propelled hot gases are allowed to pass through/on the said relevant surface with or without protective layer coating.

OBJECTIVE OF THE INVENTION

It is an object of the present invention to provide an apparatus and a method to analyze the physical, thermal and chemical properties of a material.

It is another object of the present invention to provide an apparatus and a method to analyze the physical, thermal and chemical properties of a material subjected to thermal and chemical loads or shocks during its working.

It is still another object of the present invention to provide an apparatus and a method to analyze the physical, thermal and chemical properties of a material whose output help to increase the life of the material which is subjected to thermal and chemical loads or shocks during its working.

It is yet another object of the present invention to provide an apparatus for an experiment to study and analyze the behavior of the material with or without coating on it and in a pre-determined condition which replicates actual working condition. It is a further object of the present invention to develop an apparatus for an experiment to study and analyze the behavior of the material and its manufacturing method in a pre-determined condition which replicates actual working condition. BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the present invention will now be described, with reference to the following diagrams below wherein:

Fig. 1 shows the experimental laboratory setup of an apparatus of the invention with laser pulse source and specimen material in accordance with an exemplary embodiment of the invention.

Fig. 2 shows a perspective view of the experimental lab setup of an apparatus of the invention in accordance with an exemplary embodiment of the invention.

Fig. 3 is optical micrographs of cross-sections of the laser pulse heated sample of uncoated steel substrate of HSFA AISI 4330V in combined atmosphere of super-heated steam environment and calibration gas subjected to pulses (a) 400 and (b) 600 in accordance with an exemplary embodiment of the invention.

Fig. 4 is optical micrographs of cross-sections of the laser pulse heated sample of 450 pm Tantalum coated HSFA AISI 4330V steel in combined atmosphere of super-heated steam environment and calibration gas subjected to pulses of (a) 400 (b) 600 in accordance with an exemplary embodiment of the invention.

In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.

DETAILED DESCRIPTION

As used in the specification and claims, the singular forms “a”, “an” and “the” include plural references unless the context clearly dictates otherwise. For example, the term “an article” may include a plurality of articles unless the context clearly dictates otherwise. Those with ordinary skill in the art will appreciate that the elements in the figures are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated, relative to other elements, in order to improve the understanding of the present invention. There may be additional components described in the foregoing application that are not depicted on one of the described drawings. In the event such a component is described, but not depicted in a drawing, the absence of such a drawing should not be considered as an omission of such design from the specification.

Before describing the present invention in detail, it should be observed that the present invention constitutes an apparatus of an experiment, wherein a specimen material is subjected to a laser pulse in a chemical environment as observed in its working conditions. Accordingly, the components have been represented, showing only specific details that are pertinent for an understanding of the present invention so as not to obscure the disclosure with details that will be readily apparent to those with ordinary skill in the art having the benefit of the description herein.

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting but rather to provide an understandable description of the invention.

During the research and development phase of product development, researchers generally try out different materials and coating methods in order to finalize a material and/or coating and/or coating methods which will give the best combination of life and cost for a product. For those applications where the product or system has to face a complex working condition consisting of thermal and chemical loading/shocks, a low cost testing method and apparatus is proposed in this invention. This testing apparatus and method ensures that various materials in uncoated or coated conditions can be tested under simulated work environment and their relative performance can be compared in order to finalize a material and/or coating and/or coating method combination best suited for the actual application.

FIG. 1 illustrates an experimental apparatus 100 to evaluate the specimen properties when kept in a chemical environment and subjected to thermal shocks. In one embodiment, the thermal shocks are produced using pulsating laser beam. The apparatus 100 as shown in FIG.l includes two inlets substantially tubular in shape wherein one is the calibration gas inlet 106 and other is a steam generator inlet 104. The two inlets 104 and 106 are connected to a mixer 110, wherein the calibrated gas from inlet 106 and a steam from inlet 104 are mixed to form a chemical environment similar to that found in actual working condition, for e.g. in a propulsion tube. In one embodiment, the steam is a superheated steam with maximum temperature of about 150 °C with pressure in the range of 3.5 to 4 bar. The calibrated gas has a composition and pressure which is similar to what the component experiences during actual working condition.

A stainless steel galvanized connecting pipe 128 is having two ends. At one end, there are two inlets. Valve 108 is present at one inlet of connecting pipe 128 at one end. Valve 108 is providing Nitrogen gas for purging the gas chamber 114 to create inert atmosphere inside the gas chamber 114. The outlet of mixer 110 is connected to second inlet of connecting pipe 128 having a valve 118 at that inlet. When the valve 108 is opened for purging then valve 118 is in closed condition. On closure of valve 108, the mixture of calibrated gas and superheated steam is passed into the gas chamber 114 through connecting pipe 128 by opening its valve 118.. The other end of connecting pipe 128 is connected to gas chamber 114. A flame arrestor 112 is provided in the connecting pipe 128 at other the end and nearer to the gas chamber 114. The function of flame arrestor 112 is to nullify/arrest any flames coming from the gas chamber 114 and avoids any accidents.

In one embodiment, the gas chamber 114 is preferably having a cylindrical shaped hollow interior structure wherein a specimen holder 120 is mounted on a specimen holder platform 124 with the help of nut and bolt arrangement.

In one embodiment, the specimen holder platform 124 is a flat surface. The specimen holder 120 is placed properly on this specimen holder platform 124 using designated bolt locators. The specimen holder 120 is made up of a material which has low radiation absorption capacity, for e.g. aluminium whereas specimen holder platform 124 is made up of any corrosion resistance material like SS 304 and the like. Aluminium is preferred as material to manufacture specimen holder 120 because Aluminum’s capacity to absorb heat generated by laser radiation is very less due to high heat capacity (Cp). Alternatively, any metal or material which has low heat absorption capability can be used to make the specimen holder 120. The said specimen holder 120 holds the specimen 122 to be tested or evaluated in place using nut and bolt arrangement or only bolt arrangement. This clamping arrangement of specimen 122 with specimen holder 120 avoids any unwanted movement. In one embodiment, the specimen 122 is in uncoated condition similar to the working condition of the material. In another embodiment, the specimen 122 is in coated condition similar to the working condition of the material. In another embodiment, the gas chamber 114 can be cubic or rectangular parallelepiped hollow interior in shape.

The said gas chamber 114 has a Quartz glass window 116 perpendicular to the specimen holder 120 and once the gas chamber 114 is filled with mixture of the calibrated gas and the steam, a laser pulse 126 emitted from the laser source 102 placed outside the gas chamber 114 is allowed to enter into the gas chamber 114 through the Quartz glass window 116, generating thermal shocks on the specimen 122 placed on the specimen holder 120.

In an embodiment, the laser source 102 is mounted on a bot, placed at some distance apart from, outside and above the gas chamber 114 in such a way that the laser pulse 126 emitted from laser source 102 is perpendicular to the specimen holder 120 and the window 116.

FIG. 2 illustrate a perspective view of the experimental lab setup of an apparatus. A viewing window 140 made of glass is mounted on the gas chamber 114 perpendicular to the quartz glass window 116. It facilitates the visibility of the sample 122 during the experimentation.

One problem faced during the experimental procedure is that, there is condensation of the superheated steam in mixture which is observed as it is passed in the gas chamber 114. This condensation forms droplets on the Quartz glass window 116 and also on viewing window 140 leading to attenuation of laser pulses emitted on the specimen 122 through the glass window 116 further reducing the intensity achieved on the specimen 122.

To avoid this problem, the Quartz glass windows 116 and viewing window 140 is coated with fog shield, fog repellant nano coating, which keeps the Quartz glass window 116 fog free and the laser pulses can be emitted on the specimen 122 with desired intensity.

After the termination of the laser pulses 126 emitted from laser source 102, the mixture of calibrated gas and superheated steam taken out from the gas chamber 114 through gas outlet 130 and further from helical exhaust pipe 132 as shown in FIG. 2. Further, Nitrogen gas is used for purging the gas chamber 114 from the inlet 108 to make an inert atmosphere and reduce the temperature of the exhaust gas flowing through the outlet 130.

In one preferred embodiment, the apparatus 100 for analyzing the degradation of the thermo-chemical properties in a material comprising: a) a gas chamber 114 having two inlets and one outlet; b) a connecting pipe 128 having two ends; wherein the one end is having two inlets and other end is connected to first inlet of the gas chamber 114; c) a first valve 118 attached to first inlet of the connecting pipe 128; wherein the first valve 118 controls the flow of mixture of the steam and calibrated gases; d) a second valve 108 attached to second inlet of the connecting pipe 128; wherein the second valve 108 purging the gas chamber 114 by providing nitrogen gas to create an inert atmosphere inside the gas chamber 114; e) a flame arrester 112 present in the connecting pipe 128 and nearer to the gas chamber 114 to arrest any flames coming from the gas chamber 114; f) a mixer 110 for producing the mixture of the steam and calibrated gases having two inlets and one outlet; wherein the outlet of the mixer 110 is connected to first inlet of the connecting pipe 128; g) a first inlet 104 of the mixer 110 connected to steam generator for transmitting a steam in the mixer 110 and h) a second inlet 106 of the mixer 110 connected to cylinder with calibration gas for transmitting the calibration gas in the mixer 110; wherein the calibration gas from the second inlet 106 and the steam from the first inlet 104 are mixed in the mixer 110 to form the mixture; wherein said gas chamber 114 is adapted to receive the mixture via the connecting pipe 128; i) a specimen holder 120 placed inside the gas chamber 114, mounted on a specimen holder platform 124 using either nut and bolt arrangement or bolt arrangement; wherein a specimen 122 is clamped on the specimen holder 120 using either nut and bolt arrangement or bolt arrangement; j) a window 116 in line with the specimen holder 120 present at second inlet of the gas chamber 114; k) a laser source 102 placed at some distance apart from, outside and above the gas chamber 114 such a way that the laser beam/ pulse 126 emitted by laser source 102 is perpendicular to the specimen holder 120 and the window 116, the laser beam/pulse 126 which enters into the gas chamber 114 through the window 116 and generate thermal shocks on the specimen 122 placed on the specimen holder 120; and l) a gas outlet 130 with a helical exhaust pipe 132 attached to the outlet of the gas chamber 114, wherein the mixture of calibrated gas and superheated steam is taken out from the gas chamber 114 through the gas outlet 130.

In one embodiment, the laser beam/pulse 126 emitted from the laser source 102 enters the gas chamber 114 when the gas chamber 114 is filled with mixture of the calibrated gas and the steam.

In one embodiment, the laser source 102 is mounted on a hot, said laser source is placed at predefined distance apart from, outside and above the gas chamber 114 in such a way that the laser beam/pulse 126 coming from laser source 102 is perpendicular to the specimen holder 120 and the quartz glass window 116.

In one embodiment, the steam is a superheated steam with maximum temperature of about 150°C with pressure in the range of 3.5 to 4 bar. In one embodiment, the pipe 128 is a stainless-steel galvanized pipe 128.

In one embodiment, the valve 108 is providing Nitrogen gas for purging the gas chamber 114 with Nitrogen gas to create inert atmosphere inside the gas chamber 114., keeping the valve 118 in a closed condition and on closure of the valve 108, the valve 118 is opened to pass the mixture of superheated steam and calibrated gases into the gas chamber 114.

In one embodiment, the gas chamber 114 has a hollow interior structure having a shape selected from a cylindrical shape, a cubic shape or a rectangular parallelepiped shape.

In one embodiment, the specimen holder 120 is made up of a material having low radiation absorption capacity, wherein the material is selected from Aluminium, Copper, Silver etc., whereas the specimen holder platform 124 is made up of a corrosion resistance material selected from SS 304, Inconel 718 and SS 316.

In one embodiment, the specimen 122 is in an uncoated condition or a coated condition.

In one embodiment, the window 116 is a quartz glass window.

In one embodiment, the apparatus further comprises a viewing window 140 made of glass mounted on the gas chamber perpendicular to the window 116 to facilitate the visibility of the specimen 122 during experimentation.

The steps involved in the invented testing method using the invented apparatus are enumerated below: 1. clamping the specimen 122 on the specimen holder 120 with help of nut and bolt arrangement or bolt arrangement

2. placing the specimen holder 120 (holding the specimen 122) in the gas chamber 114 on the specimen holder platform 124.

3. setting up the gas cylinder with calibration gas.

4. setting up the steam generator.

5. setting up the Nitrogen gas cylinder.

6. setting up of hot so that Laser source’s 102 emitted laser beam / pulse 126 is perpendicular to the quartz glass window 116, the specimen holder 120 and the specimen 122.

7. connecting the superheated steam generator and calibrated gas cylinder to first inlet 104 and second inlet 106 of mixer 110 respectively.

8. passing Nitrogen gas into the gas chamber 114 keeping valve 108 open and valve 118 closed for a minute.

9. spraying fog-shield onto the quartz glass window 116 and viewing window 140.

10. switching laser setup ON and providing pulses and power input.

11. closing valve 108 and opening valve 118 to let in super-heated steam and calibration gas mixture into the gas chamber 114.

12. turning on laser source 102 once mixture starts flowing through the specimen 122.

13. passing laser pulse/beam 126 through the quartz glass window 116 and allowing to hit the specimen 122 causing a thermo-chemical effect on the specimen leading to degradation of its properties.

14. turning off laser source 102 once required pulses are emitted on the specimen 122.

15. terminating superheated steam and calibration gas flow by closing the valve 118.

16. opening the valve 108 to let in Nitrogen gas into the gas chamber 114 by keeping valve 118 closed for a minute. 17. taking out the mixture of calibrated gas and superheated steam from the gas chamber 114 through the gas outlet 130 with a helical exhaust pipe 132.

18. taking away laser source 102 so that the gas chamber 114 consisting of the degraded specimen can be accessed.

19. opening the gas chamber once the gas chamber cools and taking out the specimen for testing.

The advantages of using the invented testing apparatus and method are as follows:

1. The invented testing apparatus/system is compact in size and handy.

2. The invented testing apparatus/system requires comparatively lower cost to make and operate which helps in reducing the overall development cost of the solution for life improvement.

3. The testing time required using invented apparatus and method is short as compared to testing the component in real working environment which helps in reducing the overall development timelines.

4. With less investment in time, effort and resources, good correlation is found in the results of experimental testing and actual working condition.

5. The invented testing apparatus/system is safe to operate.

6. Lower cost of testing and smaller timelines of testing ensures that a large number of variants can be tested and compared helping in faster and more informed development of solutions for component’ s life improvement.

The working of the testing apparatus and method of testing will now be explained with the help of an exemplary example: In this example, the invented testing apparatus and method were used to compare the performance of the material in uncoated (or as is) condition and with Tantalum coating.

A. Experimental Procedure: HSLA AISI 4330V Steel-Uncoated ( Substrate steel sample from propulsion/thrust tube )

1. Fix the 4330V Steel-Uncoated specimen on the Aluminium specimen holder 120.

2. Place the Aluminium specimen holder 120 (holding the 4330V Steel-Uncoated specimen 122) in the gas chamber 114 on the specimen holder platform 124.

3. Setting up the gas cylinder with calibration gas comprising of CO: 49.6%, C0₂: 12.83%, ¾: 23.93%, N₂: 13.64%.

4. Setting up the steam generator.

5. Setting up the Nitrogen gas cylinder having 99.99% Pure N2.

6. Setting up of hot arm so that laser beam /pulse 126 from YLS- 3000 Laser source 102 is in line with the quartz glass window 116 and the 4330V Steel-Uncoated specimen 122.

7. Connecting the superheated 150°C steam generator and calibrated gas cylinder to first inlet 104 and second inlet 106 of mixer 110 respectively.

8. Nitrogen gas is let into the gas chamber 114 keeping valve 108 open and valve 118 closed for a minute.

9. Fogshield is sprayed onto the quartz glass window 116 and viewing window 140.

10. YLS-3000 Laser setup is switched ON and 600 pulses and 1450 W power input is given.

11. Valve 108 is closed and valve 118 is opened to let super-heated 150°C steam and calibration gas mixture into the gas chamber 114.

12. Once mixture starts flowing through the sample, YLS-3000 Laser source 102 is turned on. 13. Laser beam 126 form from YLS-3000 Laser source 102 passes through the quartz glass window 116 and hits the 4330V Steel- Uncoated specimen 122 causing a thermo-chemical effect on the sample leading to degradation of properties. 14. Once 600 pulses are emitted on the specimen, YLS-3000 Laser gets turned off.

15. Super-heated steam and calibration gas flow is terminated.

16. Nitrogen gas is let into the gas chamber 114 keeping valve open 108 and valve 118 closed for a minute. 17. The mixture of calibrated gas and superheated steam from the gas chamber 114 is taking out through the gas outlet 130 with a helical exhaust pipe 132.

18. Laser head is taken away so that the gas chamber consisting of the laser emitted 4330V Steel-Vncoated sample can be accessed. 19. Once the gas chamber cools, gas chamber is opened and then specimen is taken out and then tested.

B. Experimental Procedure: 450m Tantalum coated HSLA AISI 4330V Steel ( Substrate steel 450m Tantalum coated sample from propulsion/thrust tube ) 1. Clamp the 450m Tantalum coated 4330V Steel specimen on the

Aluminium specimen holder 120 with help of nut and bolt arrangement or bolt arrangement.

2. Locate and place the Aluminium specimen holder 120 (holding the 450m Tantalum coated 4330V Steel specimen 122) in the gas chamber 114 on the specimen holder platform 124 with help of locators and .

3. Setting up the gas cylinder with calibration gas comprising of CO: 49.6%, C0 : 12.83%, H₂: 23.93%, N₂: 13.64%.

4. Setting up the steam generator. 5. Setting up the Nitrogen gas cylinder having 99.99% Pure N₂. 6. Setting up of bot arm so that laser beam/pulse 126 from the YLS- 3000 Laser source 102 is perpendicular to the quartz glass window 116, the specimen holder 120 and the 450m Tantalum coated 4330V Steel specimen 122. 7. Connecting the superheated 150°C steam generator and calibrated gas cylinder to first inlet 104 and second inlet 106 of mixer 110 respectively.

8. Nitrogen gas is let into the gas chamber 114 keeping valve 108 open and valve 118 closed for a minute. 9. Fogshield is sprayed onto the quartz glass window 116 and viewing window 140.

10. YLS-3000 Laser setup is switched ON and 600 pulses and 1500 W power input is given.

12. Once mixture starts flowing through the sample, YLS-3000 Laser source 102 is turned on.

13. YLS-3000 Laser beam passes through the quartz glass window 116 and hits the 450m Tantalum coated 4330V Steel specimen 122 causing a thermo-chemical effect on the sample leading to degradation of properties.

14. Once 600 pulses are emitted on the specimen, YLS-3000 Laser gets turned off.

15. Super-heated steam and calibration gas flow is terminated. 16. Nitrogen gas is let into the gas chamber 114 keeping valve open

108 and valve 118 closed for a minute.

17. The mixture of calibrated gas and superheated steam from the gas chamber 114 is taking out through the gas outlet 130 with a helical exhaust pipe 132. 18. Laser head is taken away so that the gas chamber consisting of the laser emitted 450m Tantalum coated 4330V Steel sample can be accessed.

19. Once the gas chamber cools, gas chamber is opened and then specimen is taken out and then tested.

FIG. 3 illustrates the optical micrographs of cross-sections of the laser pulse heated sample of steel substrate of uncoated HSLA AISI 4330V steel (Substrate steel sample from propulsion/thrust tube) in combined atmosphere of super-heated steam environment and calibration gas for (a) 400 pulses (b) 600 pulses, comprising a dark region 142 which is the mould material, a dark grey area 146 which is the substrate steel and the light grey regions 144 with cracks are the laser ablated regions.

The formation of heat treated zone (HTZ) or laser affected zone filled with severe cracks due to thermal shocks in steam environment are clearly visible in both the cases (a) and (b).

It can be seen that the surface degradation in FIG. 3(a) 400 pulses is severe with cracks being deep and wide and have penetrated into the substrate region 146. These cracks are generated due to thermal stresses. The depth of HTZ is around 150 pm. The material gone from HTZ regions are the loose oxides which forms when the laser heated surface melts and recrystallizes with average crack length of the crack was found to be around 97 pm.

In FIG. 3 (b) 600 pulses, more severe and deeper cracks, and wide into the substrate region 146 are clearly visible. The depth of HTZ is observed to be around 160 pm. Further, it has been observed that the depth of the laser affected zone increases as the pulses increase from 400 to 600 and the average crack length of 130 pm was observed in this 600 pulses transient thermal cycle.

Now referring to FIG. 4 which illustrates the optical micrographs of cross-sections of the laser pulse heated sample of 450 pm Cold sprayed Tantalum coated HSLA AISI 4330V steel (Substrate steel 450m Tantalum coated sample from propulsion/thrust tube) in combined atmosphere of super-heated steam environment and calibration gas for (a) 400 pulses (b) 600 pulses, comprising a dark region 134 which is the mould material, a dark grey area 136 which is a Cold sprayed Tantalum coating region of 450 pm coat and the lighter grey regions 138 is a substrate steel which is a propulsion/thrust tube part.

During experimental procedure, the transient thermal cycles of 400 and 600 laser pulses are incident on the Cold sprayed Tantalum coated layer 136, wherein during the cycle of 400 laser pulses, the surface degradation is not visible and the Cold sprayed Tantalum coating is intact. Also, the heat affected zones are not formed below the Cold sprayed Tantalum coating 136, wherein heat affect zone is the region approximately 200 microns from the surface which when affected changes the micro structure of the base material and makes it hard and more brittle. Further, there are very few minute cracks initiated along the edge of the coating 136 and also been observed to be generated on the laser heated coating surface with the average crack length was found to be around 50pm.

During the transient thermal cycle of 600 laser pulses with same experimental setup wherein the cold sprayed Tantalum coating 136 on the specimen is again 450pm, the cracks are seen to slightly propagate in the Cold sprayed Tantalum coating 136 but the interface of Cold sprayed Tantalum coating with steel substrate 138 is intact. The heat affected zone as explained above is not observed but there is slight increase in the average crack length which was found to be around 65 pm. The analysis of experimental procedure shows that cold sprayed Tantalum coating 136 sustained the thermal effect of laser pulses with calibrated gas and super heated steam environment, and the coating protects the substrate from degradation. Based on the experimental procedure followed, the 450 pm Tantalum coated specimen (Substrate steel 450p Tantalum coated sample from propulsion/thrust tube) has sustained the high temperature of the laser pulse and has remained intact as compared to uncoated specimen (Substrate steel sample from propulsion/thrust tube).

Material has been completely vanished in the some areas of heat affected zones of uncoated steel indicating a greater degree of deterioration which is not at all accepted as compared to 450p Tantalum coated steel where the coating as well as the substrate is unaffected and intact without any deterioration.

Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “consisting of’, “have”, “is” used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.

Claims

CLAIMS:

1. An apparatus 100 for analyzing degradation of thermo-chemical properties in a material, said apparatus 100 comprising: a) a gas chamber 114 having two inlets and one outlet; b) a connecting pipe 128 having two ends; wherein the one end is having two inlets and other end is connected to first inlet of the gas chamber 114; c) a first valve 118 attached to a first inlet of the connecting pipe 128; wherein the first valve 118 controls the flow of mixture of the steam and calibrated gases; d) a second valve 108 attached to a second inlet of the connecting pipe 128; wherein the second valve 108 purging the gas chamber 114 by providing nitrogen gas to create an inert atmosphere inside the gas chamber 114; e) a flame arrester 112 present in the connecting pipe 128 and nearer to the gas chamber 114 to arrest any flames coming from the gas chamber 114; f) a mixer 110 for producing the mixture of the steam and calibrated gases having two inlets and one outlet; wherein the outlet of the mixer 110 is connected to first inlet of the connecting pipe 128; g) a first inlet 104 of the mixer 110 connected to steam generator for transmitting steam in the mixer 110; h) a second inlet 106 of the mixer 110 connected to cylinder with calibration gas for transmitting the calibration gas in the mixer 110; wherein the calibration gas from the second inlet 106 and the steam from the first inlet 104 are mixed in the mixer 110 to form the mixture; wherein said gas chamber 114 is adapted to receive the mixture via the connecting pipe 128; i) a specimen holder 120, placed inside the gas chamber 114, mounted on a specimen holder platform 124 using either nut and bolt arrangement or bolt arrangement; wherein a specimen 122 is clamped on the specimen holder 120 using either nut and bolt arrangement or bolt arrangement; j) a window 116 in line with the specimen holder 120 present at second inlet of the gas chamber 114; k) a laser source 102 placed outside and above the gas chamber 114 and in line with the specimen holder 120 and the window 116, to emit a laser pulse 126 which enters into the gas chamber 114 through the window 116 and generate thermal shocks on the specimen 122 placed on the specimen holder 120; and l) a gas outlet 130 with a helical exhaust pipe 132 attached to the outlet of the gas chamber 114; wherein the mixture of calibrated gas and superheated steam is taken out from the gas chamber 114 through the gas outlet 130.

2. The apparatus as claimed in claim 1, wherein the laser source 102 is mounted on a hot, said laser source 102 is placed apart from and above the gas chamber 114; wherein the laser pulse 126 emitted from the laser source 102 is perpendicular to the specimen holder 120 and the window 116.

3. The apparatus as claimed in claim 1, wherein the laser pulse 126 emitted from the laser source 102 enters the gas chamber 114 when the gas chamber 114 is filled with mixture of the calibrated gas and the steam.

4. The apparatus as claimed in claim 1, wherein the steam is superheated steam with maximum temperature of about 150 °C with pressure in the range of 3.5 to 4 bar.

5. The apparatus as claimed in claim 1, wherein the pipe 128 is a stainless-steel galvanized pipe 128.

6. The apparatus as claimed in claim 1, wherein the valve 108 is purged with Nitrogen gas to create inert atmosphere, keeping the valve 118 in a closed condition and on closure of the valve 108, the valve 118 is opened to pass the mixture into the gas chamber 114.

7. The apparatus as claimed in claim 1, wherein the gas chamber 114 has a hollow interior structure having a shape selected from a cylindrical shape, a cubic shape, or a rectangular parallelepiped shape.

8. The apparatus as claimed in claim 1, wherein the specimen holder 120 is made up of a material having low radiation absorption capacity, wherein the material is selected from Aluminium, Copper, Silver, whereas the specimen holder platform 124 is made up of a corrosion resistance material selected from SS 304, Inconel 718, and SS 316.

9. The apparatus as claimed in claim 1, wherein the specimen 122 is in an uncoated condition or a coated condition.

10. The apparatus as claimed in claim 1, wherein the window 116 is a quartz glass window.

11. The apparatus as claimed in claim 1, wherein the apparatus further comprises a viewing window 140 made of glass mounted on the gas chamber perpendicular to the window 116 to facilitate the visibility of the sample during experimentation.

12. A method for analyzing the degradation of the thermo-chemical properties in a material comprising: a. clamping the specimen 122 on the specimen holder 120 with help of nut and bolt arrangement or bolt arrangement; b. placing the specimen holder 120 (holding the specimen 122) in the gas chamber 114 on the specimen holder platform 124 with help of locators and; c. setting up the gas cylinder with calibration gas; d. setting up the steam generator; e. setting up the Nitrogen gas cylinder; f. setting up of the hot so that laser beam/pulse 126 from the laser source 102 is perpendicular to the quartz glass window 116, the specimen holder 120 and specimen 122; g. connecting the superheated steam generator and calibrated gas cylinder to the first inlet 104 and the second inlet 106 of mixer 110 respectively; h. passing Nitrogen gas into the gas chamber 114 keeping the valve 108 open and the valve 118 closed for a minute; i. spraying fog-shield onto the quartz glass window 116 and the viewing window 140; j. switching laser setup ON and providing pulses and power input; k. closing the valve 108 and opening the valve 118 to let in super heated steam and calibration gas mixture into the gas chamber 114; l. turning on the laser source 102 once mixture starts flowing through the specimen 122; m. passing laser beam/pulse 126 through the quartz glass window 116 and allowing to hit the specimen 122 causing a thermo- chemical effect on the specimen leading to degradation of its properties; n. turning off laser source 102 once required pulses are emitted on the specimen 122; o. terminating superheated steam and calibration gas flow by closing the valve 118; p. opening the valve 108 to let in Nitrogen gas into the gas chamber 114 by keeping valve 118 closed for a minute; q. taking out the mixture of calibrated gas and superheated steam from the gas chamber 114 through the gas outlet 130 with a helical exhaust pipe 132; r. taking away laser source 102 so that the gas chamber 114 consisting of the degraded specimen can be accessed; and s. opening the gas chamber once the gas chamber cools and taking out the specimen for testing.