Luminescent material matrix composites for remote structural deformation and wear detection

The present invention concerns a method for production of a component comprising at least one luminescent material matrix composite, the corresponding component and an employment of the component .

Metallic parts can fail in their application depending on the applied load, wear, temperature induced plastic behavior, chemical environment, etc. This in turn can have fatal conse ^¬ quences for machinery and humans if not detected in time and replaced.

To detect material damage, such as corrosion, surface coating ablation, cracks, wear or creep, the most commonly used method of inspection is visual inspection by humans. This normal- ly implies the stopping of machines and the physical presence of personal. Conventional non-destructive testing methods, such as ultra sonic wave monitoring, eddie-currents , electri ^¬ cal gauging, vibration sensing, have also been used for remote material inspection and control.

It is an object of the present invention to find an easy, in ^¬ expensive and efficient way to detect material damage par ^¬ ticularly caused by corrosion, surface coating ablation, cracks, wear or creep in particular under specific physical or chemical environment conditions like a load, temperature, acidity or humidity. Especially metallic parts or components should be inspected during or after their application to avoid failure. A remote non-destructive testing should be possible .

The object of the invention is solved by a component accord ^¬ ing to an accessory claim, an employment of the component ac- cording to another accessory claim, and a method of production of the component according to the main claim.

According to a first aspect a method for production of a com- ponent comprising at least one luminescent material matrix composite is suggested, performing the steps of providing a mixture by mixing a luminescent material with a matrix mate ^¬ rial with a concentration ratio, providing the composite by a heat treatment of the mixture by a temperature process under pressure, whereby the luminescent property of the luminescent material is preserved in the composite, positioning the com ^¬ posite in or on a component region.

According to a second aspect a component comprising at least one luminescent material matrix composite is suggested, whereby a mixture of the luminescent material with the matrix material with a concentration ratio is provided, the lumines ^¬ cent property of the luminescent material is preserved in the composite, the composite is positioned in or on a component region.

According to a third aspect and an employment of a component, in particular a component of the present invention, for inspection of the component is claimed, whereby the steps lo- calizing the composite in or on a component region being sub ^¬ jected to at least one degradation effect, exposing the com ^¬ ponent region to excitation energy and detecting of luminescence radiation depending on a degree of degradation are performed .

Further advantages embodiments are claimed by the subclaims.

According to an embodiment before mixing each of the lumines ^¬ cent material and the matrix material can be a powder.

According to another embodiment in the composite the lumines ^¬ cent material can be a phosphor and/or the matrix material can be metallic. The invention refers to a low cost solution to the object of this application, by incorporating of luminescent phosphor- metal composite (LPMC) for remote material damage detection.

The invention also refers to the method of production of men ^¬ tioned LPMCs and their possible incorporation in several com ^¬ ponents . According to a further embodiment in the composite the phos ^¬ phor can be rare earth doped oxides, nitrides or oxinitrides, in particular YAG:Ce.

According to another embodiment in the composite the metallic material can be a Ni- or Co-super-alloy, structural steel, a hard metal, a refractory metal, a carbide or a nitride.

According to another advantageous embodiment in the composite the luminescent material can comprise a concentration between 0,1-50 Vol-%, in particular in between 1-10 Vol-%.

According to another advantageous embodiment the heat treat ^¬ ment is sintering, in particular is spark-plasma-sintering (SPS) , and/or the pressure is uniaxial. Spark-plasma- sintering allows for the rapid sintering of ceramic and pow ^¬ der metallurgical parts. The fast sintering capabilities of the spark-plasma-sintering could facilitate the mixture and sintering of materials which would otherwise react with each other, due to atomic diffusion processes, whereby each single material could lose its initial chemical or physical proper ^¬ ties. Properties that could however be desired to preserve in a composite design. The heat treatment for preserving the lu ^¬ minescent property of the luminescent materiel in the compos ^¬ ite is also advantageously performed by other field assisted sintering techniques (FAST) , for example by electric dis ^¬ charge sintering. Moreover all these sintering methods using electrical heating are found to be useable for this preserv ^¬ ing purpose. According to another advantageous embodiment the sinter tem ^¬ perature process can be around 1000 °C-1300 °C under pressure of 30-40MPa for about 5-15 minutes.

According to a further advantageous embodiment in the compo ^¬ site the luminescent material and the matrix material are ho ^¬ mogeneously mixed and luminescent particles are dispersed evenly throughout the matrix.

According to another advantageous embodiment in the composite luminescent particles can be dispersed within a subsurface layer inside the matrix. According to a further advantageous embodiment the composite can be a multilayer stack comprising layers of different concentration ratios.

According to a further advantageous embodiment the multilayer stack can be created by laminating of tape-casted green foils having different concentration ratios.

According to a further advantageous embodiment the layer con ^¬ centration of the luminescent material can be increasingly provided with a depth of the component.

According to a further advantageous embodiment of the present invention the layer concentration of the luminescent material in an outermost layer can be 0.

According to a further advantageous embodiment the multilayer stack can comprise a cylindrical shape.

According to a further advantageous embodiment the position- ing can be performed by incorporating of the composite into a metallic component by welding, diffusion bonding, laminating, hot pressing, the heat treatment and/or via surface covering configuration . According to a further advantageous embodiment the composite can be a billet or a sheet or a bulky physical body. According to a further advantageous embodiment the position ^¬ ing can be performed by incorporating of the composite into a metallic component by welding, diffusion bonding, laminating, hot pressing and/or the sintering. According to a further advantageous embodiment the position ^¬ ing can be performed by depositing of the composite on to the surface of a metallic component in particular by structural laminating . According to a further advantageous embodiment the position ^¬ ing can be performed by positioning the composite at a coor ^¬ dinate position on the component surface. Correspondingly a plurality of coordinate positions can be created. According to a further advantageous embodiment a plurality of luminescent material matrix composites can be used.

According to a further advantageous embodiment a plurality of luminescent material matrix composites can be positioned in particular along a line or according to a grade. The composites can be positioned on crossing points of the grade.

According to a further advantageous embodiment the component can be a machine or a functional technical system or a metal- lie structure or a mechanically or chemically or physically stressed physical body or can be a part, particularly a move ^¬ able part, of it.

According to a further advantageous embodiment the component can be a brake pad, a tube, a turbine, a turbine vane or a contact . According to a further advantageous embodiment of the inven ^¬ tion an employment can be such that localizing the composite inside the component region being subjected to the degrada ^¬ tion effect, exposing the component region to excitation en- ergy from outside of the component, detecting the lumines ^¬ cence radiation depending on an amount of emitting luminescent particles.

According to a further advantageous embodiment the employment can be localizing of composite coordinate position (s) on the component surface, the component being subjected to at least one deformation effect, exposing the component surface to ex ^¬ citation energy, and detecting the luminescence radiation depending on coordinate position (s) shift (s) of the composi- tion.

According to a further advantageous embodiment the detecting of the luminescence radiation can be performed by a human eye or by a photodiode transforming the luminescence radiation into an electrical signal.

According to a further advantageous embodiment the detecting of coordinate position (s) of the luminescence radiation can be performed by a photo analyzer unit.

According to a further advantageous embodiment the excitation energy can be provided by illuminating the component region by ultra violet and/or visible light. According to a further advantageous embodiment localizing of the composite in or on the component region can be performed by permanently fixing an excitation energy source and a luminescence radiation detector relative to the component. The invention will be described by embodiments in connection with the figures. It shows:

Fig. 1 a first embodiment of an inventive component; Fig. 2 a second embodiment of an inventive component;

Fig. 3 a third embodiment of an inventive component;

Fig. 4 a fourth embodiment of an inventive component;

Fig. 5 a fifth embodiment of an inventive component; Fig. 6 a sixth embodiment of an inventive component;

Fig. 7 a seventh embodiment of an inventive component and an inventive employment; Fig. 8 an eighth embodiment of an inventive component and an inventive employment;

Fig. 9 a first embodiment of an inventive production meth ^¬ od;

Fig. 10 a first embodiment of an inventive employment; Fig. 11 an embodiment of an inventive composite. Fig. 1 shows a first embodiment of an inventive component 1 comprising an inventive composite 3. Fig. 1 shows a component 1 comprising at least one luminescent material matrix compo ^¬ site 3, whereby the component 1 is created by the composite 3. The component 1 comprises at least the one luminescent ma- terial matrix composite 3. The composite 3 is a mixture of the luminescent material 5 with the matrix material 7 at a certain concentration ratio. The luminescent property of the luminescent material 5 is preserved within the composite 3. The composite 3 is positioned in or on a component 1 region. The composite 3 can form the component 1. For example the lu ^¬ minescent material 5 can be phosphor. The matrix material 7 can be a metal. According to Fig. 1 the phosphor and the met- al homogenously mixed and the phosphor particles are dis ^¬ persed evenly throughout the metallic matrix.

Fig. 2 shows a second embodiment of an inventive component 1. A composite 3 according to Fig. 2 is a multilayer stack comprising layers of different concentration ratios. For example the luminescent phosphor metal composite (LPMC) is built up of layers of different phosphor to metal concentrations in a multilayer stack. This could e. g. be achieved by the lamina- tion of tape-casted green foils having different composition ^¬ al concentrations, and which thickness can be easily con ^¬ trolled. According to this embodiment the layer concentration of the luminescent material 5 increases with the depths of the component 1. Again, the component 1 can be formed by the composite 3 or the composite 3 is incorporated into the com ^¬ ponent 1. Also, according to Fig. 1 in the top layer the lay ^¬ er concentration of the luminescent material 5 is 0. This lu ^¬ minescent phosphor metal composite (LPMC) can be used for re ^¬ mote wear, corrosion, coating ablation and crack sensing. The LPMC is incorporated into a part or a region of a part of the component 1 being especially subjected to the degradation ef ^¬ fect. When the LPMC is made visible through the above men ^¬ tioned defect, and illuminated for example by ultra-violet UV or visible light, the phosphor particles in the LPMC will il- luminate. This could either be visual by the naked eye or sensed by a photodiode that transforms the illumination into an electrical signal. In a multilayer set-up the concentra ^¬ tion gradient could be used to remotely sense a depth of wear dependant on the concentration level reached and thus an electrical signal is produced.

Although not circumventing the final visual inspection by humans, the remote sensing of material failure by the use of the proposed LPMC-material could give a first warning signal.

Fig. 3 shows a third embodiment of an inventive component 1. Again the composite 3 can be incorporated into the component 1 or can form the component 1. According to this embodiment the composite luminescent particles 5 are dispersed within a subsurface layer inside the matrix 7.

Fig. 4 shows a fourth embodiment of an inventive component 1. According to this embodiment the multilayer stack of Fig. 2 is formed to a cylindrical shape. Cylindrical shapes could be done in a similar multilayer set-up, or parts of any shape could be coated with the LPMC or corresponding materials. The incorporation of mentioned LPMCs into other metallic parts could be done by welding, diffusion bonding, lamination, hot pressing, spark-plasma-sintering and so on. For example a LPMC-layer could be applied in a surface covering configura ^¬ tion . Fig. 5 shows a fifth embodiment of an inventive component 1. According to this embodiment the composite 3 is provided as a billet or a sheet or as a bulky body. With the elevated costs of phosphor materials in mind, the LPMCs could be incorpo ^¬ rated as billets.

Fig. 6 shows a sixth embodiment of an inventive component 1. The composite 3 is hereby incorporated as a billet in the body of the component 1. In this case the component 1 can be an axis of rotation, which is indicated by "ω".

Fig. 7 shows a seventh embodiment of an inventive component 1 and another inventive employment. According to Fig. 7 LPMCs billets or sheets are attached to or immersed in the surfaced of a metallic part forming the component 1. For example the billets could be laminated into a metallic surface in a structured way. By mapping the coordinate position of each LPMC coordinate it would give the possibility to remotely sense if the metallic part being the component 1 has been subjected to mechanical deformation, due to an impact or through thermo or mechanical creep. If this happens, the po ^¬ sition of the LPMC is changed and it could be remotely de ^¬ tected by illumination and photo analysis of the new coordi ^¬ nates of the composite, composites 3 and/or of the LPMCs. Fig. 8 shows an eighth embodiment of an inventive component 1. The component 1 hereby is an axis of rotation indicated by "ω". Also according to this embodiment the composite coordi- nate positions on the component 1 surface are localized. The component 1 is subjected to at least one deformation effect. By exposing the component 1 surface to excitation energy, which is for example ultra-violet light, the luminescence ra ^¬ diation depending on the coordinate positions and their shifts of the composite 1 can be detected. Fig. 8 shows a lengthening of the component 1. In contrast to this Fig. 7 shows a distortion of an component 1.

Fig. 9 shows an embodiment of an inventive production method. A component 1 comprising at least one luminescent material matrix composite 3 should be produced. A first step SI is providing a mixture by mixing a luminescent material with a matrix material with a concentration ratio. According to a second step S2 the composite is provided by a heat treatment of the mixture by a temperature process under pressure, whereby the luminescent property of the luminescent material is preserved in the composite. With a third step S3 the com ^¬ posite is positioned in or on a component region to be in ^¬ spected .

Fig. 10 shows an embodiment of an inventive employment of an inventive component 1. By a first step SI at least one compo ^¬ site is localized in or on a component region of the compo ^¬ nent 1 being subjected to at least one degradation effect. By a second step S2 this component region is exposed to excita ^¬ tion energy. By a third step S3 the detected luminescence ra ^¬ diation shows a degree of degradation. A degree of degrada ^¬ tion is proportional to an amount of detected luminescent ra ^¬ diation or is proportional to a coordinate position shift.

Other further employment embodiments can be as follows. It is possible to provide a remote material wearing sensor for me ^¬ chanically moveable parts can be provided. Good examples could be the covering of train brakes or train wheels. When a certain depth of the material was removed by wearing, it would be possible to detect by an excitation source metal- phosphor-composites inside the material. A photo diode could detect the generated light.

A further employment would be in the process industry, e. g. petro-chemistry . By chemical or temperature or acidic environments materials can be stressed extremely. Those materials can corrode. Such processes are also remotely detectible by the idea of this invention.

For example a pipe inspection robot can perform an inventive inspection. The employment is also useful for the detection of ablation of functional layers. An example would be gas turbines and their TBC-layers. A composite radiant structure should facilitate integration into a turbine vane. Detection of erosion and corrosion and of ablation processes would be possible. Additionally, within turbines or other metallic structures could be prepared for creep detection. Alterna ^¬ tively after an earth quake deformation of metallic struc ^¬ tures could be explored. In this case inventive composites are laminated in or on component structures as a coordinate structure. Another inventive employment is the inspection of contact materials where electrical erosion usually takes place and the material is damaged.

Fig. 11 shows another embodiment of an inventive composite 3. According to this embodiment a LPMC containing 20 Vol-%

YAG:Ce in 80 Vol-% of a nickel super alloy was mixed (Rene 80) . The phosphor metal mixture was then spark-plasma- sintered at 11050°C for 10 minutes under the uniaxial pres ^¬ sure of 35MPa. Fig. 11 shows the microstructure of the frac ^¬ tion surface from a LPMC with the above mentioned composi- tion. It is understood that the current invention is not re ^¬ stricted to the above listed materials in the above listed concentrations, but could be any type of phosphor and metal ^¬ lic composite mixture at any type of concentration. Other compositions are also possible. For example, as the lumines ^¬ cent material the following phosphors could be used:

Rare earth doped oxide, nitrides, ox nitrides, e. g. for YAG:Ce. As metallic material the following could be used: Ni and Co superalloys, structural steels, hard metals, refracto ^¬ ry metals, carbides, nitrides etc. A luminescent concentra ^¬ tion between 0.1-50 Vol-% is preferably used, more specifi ^¬ cally between 1-10 Vol-%. The principle is to mix materials with different chemistry, in particular metallic superalloys plus phosphor ceramic, by spark-plasma-sintering showed advantageous effects. A piece of these composites has proven that luminescence still takes place by excitation especially by ultra-violet or blue light. It is especially interesting that a spark-plasma-sintering process allowed a short sinter time below 30 minutes, and this process allows that the luminescent material keeps its luminescent properties. The invention refers to a component 1 comprising at least one luminescent material matrix composite 3, whereby

- a mixture of the luminescent material 5 with the matrix ma ^¬ terial 7 with a concentration ratio is provided;

- the luminescent property of the luminescent material 5 is preserved in the composite 3;

- the composite 3 is positioned in or on a component 1 re ^¬ gion. The invention also refers to the production of the component 1 and its employment for remote structural deformation and wear detection.