CN103879124A

CN103879124A - Method and device for producing a panel formed from glued boards

Info

Publication number: CN103879124A
Application number: CN201310712754.5A
Authority: CN
Inventors: 达里奥·通切利
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-12-21
Filing date: 2013-12-20
Publication date: 2014-06-25
Also published as: ES2493365R1; ES2493365A2; ITTV20120241A1; ES2493365B1

Abstract

The present invention relates to a method and apparatus for manufacturing panels formed of glued boards. A method for manufacturing an article in the form of a composite panel (12) comprising at least a first sheet (14) and a second sheet (16), comprising the steps of: dispensing adhesive (18) onto one side (141, 161) of at least one panel (14, 16); placing the plates (14, 16) under vacuum; joining together two panels (14, 16) to form a composite panel (12); and exposing the panel (12) to atmospheric pressure.

Description

For the manufacture of the method and apparatus of the panel being formed by the plate gluing together

The present invention relates to for the manufacture of on the top that is arranged in another by and be glued to the method and apparatus of the composite panel (composite panel) that plate together forms.

In the prior art, the panel forming by least two boards that connects together is known, and these comprise by putting into the cladding plate conventionally with attracting outward appearance (cladding sheet) that for example adhesive based on resin of adhesive connects together such as natural stone material and the gripper shoe of being conventionally made up of coalescence material (agglomerated material) or ceramic material.

That prior art is known for the manufacture of the distinct methods of this type of plate connecting together.

According to the first method, then the connecting surface and this plate that are coated with equably a plate with adhesive connect together with the second plate, if desired, apply mechanical pressure, until adhesive hardens.But this method has following major defect: air is trapped in gummed region, along with the past of time, the problem of bonding strength occurs.

With the nominal European patent EP 1812360 of Luca Toncelli, the method that wherein two boards connects together by the adhesive being arranged in is therebetween described.Adhesive is applied on the first plate, makes to exist some regions of suitably arranging that there is no in fact adhesive on surface.Then, the second plate and the surface that has been coated with the first plate of adhesive on it are relatively positioned.The panel of assembling in advance so obtaining is inserted into vacuum indoor therein, and two boards is pressed into together, makes compressed adhesive form as far as possible evenly and not have the layer of air pocket (air pocket).

There is no in fact the surf zone of adhesive and vacuum to have just in time to play restriction as much as possible to be still captured in the effect of the air in adhesive phase.Especially, once the second plate is positioned on the first plate, do not have in fact the region of adhesive to produce the passage conventionally communicating with the transverse edge of the plate of assembling in advance, make the suction being produced by vacuum force caught air to be discharged from adhesive phase, pass along clear passage.

Although extensively established, prior art is imperfect.

In fact, have been noted that, although extreme care when the pearl of adhesive disposed, if but do not have in fact some regions of adhesive to be occupied by adhesive prematurely, allow some in the passage of the fluid communication between related surperficial core and lateral edge to get clogged.This situation has hindered the Bas Discharged between two opposed face (facing surface) of two boards.

Meanwhile, adhesive can distribute in inhomogeneous mode, leaves the some regions that there is no adhesive completely, and the defective gummed subsequently of plate.

Especially in the time that air pocket is positioned near the edge of connecting plate, because they have formed zone of fracture (fracture prime) or point that water wherein or other liquid can infiltrate, therefore air pocket has weakened the gummed between two boards.Under extreme case, likely plate can also separate.

If rest on the plate of pearl top weighs very much, problem worse, because in one aspect, pearl should have the denseness of pastel sample (paste-like), it is fully dense to avoid compressed before discharging air, but in yet another aspect, denseness should fully flow, to allow the uniform distribution of adhesive.

In order to overcome the problem of premature compression of adhesive, therefore conventionally tend to use relatively dense adhesive and for by plate against each other and the device of compressive plate, this device is enough powerful in sufficient compression to be provided, although the pastel sample attribute of adhesive.This causes having relatively high power and being therefore relatively costly by the needs of pressing system.But although use these by pressing system, in any case, the pastel sample attribute of adhesive can produce the uneven distribution of adhesive between the compression period of plate.

In order to guarantee that air discharges along the passage being formed by adhesive, also need to use relatively high vacuum and/or relatively long vacuum open-assembly time.It is relatively costly that first condition causes vacuum plant, and second condition slows down a large amount of productions of panel simultaneously.

Therefore, the object of the invention is to overcome at least in part the shortcoming of prior art.

First task of the present invention is the production that allows to have the composite plate panel of effective distribution of the adhesive between plate.

The second task of the present invention is to obtain composite panel, and air can be still captured in the layer of the adhesive between plate.

With realizing object and task according to the equipment of claim 1 with by method according to Claim 8.

With reference to accompanying drawing, the characteristic feature of method and apparatus according to the invention and benefit will more clearly present from the description of some limiting examples of embodiment provided below, in accompanying drawing:

Fig. 1 shows according to a part for equipment of the present invention;

Fig. 2 a-2g be presented under different operating conditions according to a part for the equipment of Fig. 1;

Fig. 3 shows according to the top view of a part for equipment of the present invention;

Fig. 4 shows according to the side view of a part for the equipment of Fig. 3;

Fig. 5-7 show three steps for two boards is connected together of the method according to this invention; And

Fig. 8 and Fig. 9 show two steps for three blocks of plates are connected together of the method according to this invention.

Especially with reference to figure 5-7, composite panel 12 constructed in accordance comprises at least the first plate 14 and the second plate 16 that expection connects together Face to face by the adhesive phase being arranged in therebetween.

Each

piece plate

14,16 comprises respectively by 141 and 161 the first sides that represent or surface, respectively by 142 and 162 the second sides that represent or surface and respectively by the 143 and 163 peripheral sides edges that represent.Expection together with 162 are glued to, expects that

side

142 and 161 becomes the exterior lateral sides of composite panel by side 141 simultaneously.

Advantageously, can be made by coalescence material or ceramic material for one in two boards, and another piece plate can be cladding plate, conventionally be made by natural stone material.

According to the method for the goods of the form for the manufacture of with composite panel 12, suitable adhesive 18 is coated on a side of at least one block of

plate

14,16, and the

plate

14,16 also not connecting together is placed in vacuum environment.

Adhesive can advantageously be coated with onboard with the form of parallel pearl.

Once be placed in a vacuum, the adhesive that two

boards

14,16 use are arranged in therebetween connects together, to form composite panel 12.After this operation, the panel 12 forming thus can be exposed to atmospheric pressure again.

Can and panel be exposed to again between the step of atmospheric pressure at Connection Step and carry out for plate is pressed into step together simultaneously.

With reference to figure 8 and Fig. 9, the possible version of the method according to this invention has been imagined with two composite panels 12 of three blocks of plates, 14,16,17 acquisitions that connect together.According to this version, plate 14 is used as intermediate plate and is glued between two

outside plates

16 and 17, afterwards, adhesive 18 (is for example coated on the side being connected to together, in the top-side of plate 14 and 17), and under the condition that they are not also joined together therein, three blocks of plates are placed under vacuum.Once all three blocks of plates connect together under vacuum, and panel is exposed to atmospheric pressure again, and by intermediate plate 14 along its thickness, be parallel to gummed panel cut in half, to obtain two independent panels, as in Fig. 9 schematically show.Advantageously, intermediate plate 14 can be made up of natural stone.According to the method, three blocks of

plates

14,16 are connected together with 17 can two continuous steps carry out, and first under vacuum, makes two boards be glued to together and and then under vacuum, the 3rd plate is glued in the two boards of beginning.

Advantageously, two boards 16 can be made up of for example ceramic material of similar material with 17.

According to possible embodiment of the present invention, adhesive 18 can comprise mastic (mastic) or liquid resin and filler.Advantageously, resin can be epoxy resin, polyurethane or organic siliconresin.

Advantageously, in order to obtain good result, before plate being connected together under vacuum, can under vacuum, prepare adhesive 18, with prevent air be hunted down and avoid during air extraction swelling/mousse (mousse) effect.

As mentioned above, according to possible preferred embodiment of the present invention, for making the step that plate connects together and wherein making panel (thering are two and/or three blocks of plates) again be exposed between the step of atmospheric pressure, can also exist and wherein apply suitable power so that plate moves together and the step of compression binder layer.Advantageously, apply for making power that plate moves together corresponding to being equal to or greater than 0.05N/cm ²pressure, continue duration of 1-10 second.

The coating of adhesive 18 can also be carried out under vacuum.

Advantageously, the vacuum producing in the environment that makes therein plate 14,16 connect together can have 80 and 120mbar between residual pressure.

Making after plate connects together, the method can comprise fine finishining step (finishing step), in fine finishining step, composite panel 12 is cut into suitable dimension, smoothing and/or polishing.For example, can be advantageously, one in two boards is made with the size that is greater than another piece plate, to be beneficial to location in the time connecting together.Then the excessive marginal portion that, the plate (be generally gripper shoe, it is more cheap than the cladding plate of being made up of marble or other quality material) of large-size has been removed in deburring subsequently operation (trimming operation).

With reference to figure 1, will describe according to equipment of the present invention embodiment.

Equipment for the manufacture of the goods of the form of the composite panel 12 of at least the first plate 14 connecting together with the adhesive comprising by being arranged in therebetween and the second plate 16 comprises the join domain 125 that is suitable for being placed under vacuum.Join domain comprises and is suitable for manipulation device (handling means) 128 that

plate

14,16 is connected together.

According to possible embodiment of the present invention, join domain 125 comprises and is suitable for coordinating to be created in stayed surface 124 bell-shaped element (bell-shaped element) 126 that wherein forms the environment of vacuum via vacuum plant (not showing, because those skilled in the art can easily expect them).Advantageously, bell-shaped element 126 is adapted to pass through known vertical movement apparatus (for example, pneumatic or hydraulic piston) 130 and raises and decline towards stayed surface 124 from stayed surface 124.

Plate can arrive the position (by suitable transportation system) of manipulation device successively, for example, after the general known adhesive coating device by 147 expressions.

Manipulation device can also be realized compression or the press device for press upper plate against base plate.Advantageously, transportation system comprises conveyer 124, and conveyer 124 is also formed on the stayed surface of bell-shaped element 126 belows.

As noticed from Fig. 1, in the upstream of join domain 125, advantageously, be for example provided with a series of plate 14(of adhesive pearl, Ceramic Tiles) and a series of plate 16(for example formed by marble slab) place with the order replacing.Advantageously, plate 14 is those plates that must work as gripper shoe in panel, and plate 16 is those plates that must work as cladding plate in panel.

As seen in more detail hereinafter, manipulation device can be designed to process several plates below bell-shaped element simultaneously.Therefore, the number of the plate in each series will be lucky (very).

For example, Fig. 1 shows each a series of plate that comprises 5 rows.As below will seen, each row can also comprise several plates that are juxtaposed to each other, and for example three blocks of plates obtain the whole 15 blocks of plates altogether in simultaneously treated each group in vacuum join domain 125.

The number of row's number and each row's plate can also change, and depends on the size of plate and the size of bell-shaped element 126.

As can understand from Fig. 1 and as among Fig. 2 a, Fig. 2 g, show successively in more detail, in equipment 1, in the time that conveyer belt 124 advances, a series of plate 16 relatively locates with the manipulation device 128 in join domain below the bell-shaped element of rising that (Fig. 2 is a).

Then manipulation device 128 declines, to capture a series of plate 16(Fig. 2 b).According to shown in embodiment, manipulation device 128 can be advantageously supported on bell-shaped element 126 inside with therewith move and and then there is actuator 131, this actuator 131 is for carrying out in the inner extra motion of advancing downwards of bell-shaped element, can and for example moving in bell-shaped element between the down position shown in Fig. 2 b at raised position as shown in Figure 2 a of example.In primary importance, the crawl end 129 of manipulation device is retracted about the edge of bell-shaped element, and in the second place, in the time that bell-shaped element abutment surface 124 reduces, these capture end and move down, to arrive the plate on surface 124.

Capture end 129 and can advantageously comprise known suction cup raising device (suction-cup raising means) (for example, suction surface), the top-side of the plate below suction cup raising device can be attached in the time of operation.

After bell-shaped element and relevant plate manipulation device 128 have declined, manipulation device is caught plate (especially, vacuum is stopped onboard and produced in suction cup to suction cup), and plate 16 is booked, and (Fig. 2 b).The environment of bell-shaped element remains under atmospheric pressure.

Afterwards, bell original paper and manipulation device are raised, and raised (Fig. 2 c) from stayed surface to make plate.

At this moment, conveyer belt 124 moves forward again, and the plate 14 until a series of with adhesive is positioned in that bell-shaped element is inner and (Fig. 2 d) in the appropriate location corresponding to the plate supporting by manipulation device 128 definitely.

Bell-shaped element 126 drops on surface 124 again in the mode of sealing, and manipulation device 128 keeps raising, and (Fig. 2 e) in the interior generation vacuum of bell-shaped element 126.Thinking that a certain predetermined time that is suitable for fully removing air between bell-shaped element and plate is section, manipulation device 128 reduces, and on the corresponding plate 14 of adhesive, (Fig. 2 f) against being coated with thereon to make plate 16.

Only forming after vacuum, the plate at top is being placed on the plate of bottom.By this way, guarantee not have air to be still trapped between plate.

The manipulation device 28 that is provided with suction cup surface in use, the vacuum in suction cup must be greater than the vacuum in bell-shaped element, departs from suction cup and falls with the plate that prevents top.This can easily realize, because need to not exist very high vacuum can remove the air between plate, be different from the prior art deflating the labyrinth (labyrinth) must the adhesive between the plate by having contacted with each other forming in bell-shaped element.

For example, use the residual pressure (for example about 100mbar) of 80-120mbar in bell-shaped element and use the suction cup of intended size, the residual pressure in suction cup can be about 25-35mbar(for example, about 30mbar).

After in gripper shoe below top plate is placed on, by operate actuator 131 suitably, plate is pressed into together by the power regulating, with the pearl of compression binder and produce the uniform layer of adhesive, plate is adhered to each other securely simultaneously.

Then, the manipulation device 128 of stopping using, (Fig. 2 is g) to make their release boards and rising bell-shaped element.

At this moment, band moves forward, and makes the composite panel 12 forming thus can move away join domain 125 and new a series of plate 16 can be positioned to the below of bell-shaped element, thereby circulation is restarted simultaneously.

As seen from Fig. 1 and Fig. 2, bottom plate 14 can also be arranged on the top that rests in groups stayed surface 124, and stayed surface 124 can be beneficial at panel the manipulation of panel in groups after the interior formation of bell-shaped element 126.

As described above, manipulation device 128 can advantageously comprise suction cup system.The necessary suction force of suction cup device will depend on their size and size and the weight of plate to be raise significantly, also considers that these devices must also operate in the environment under the condition that has the negative pressure compared with normal atmosphere pressure.

According to selectable embodiment of the present invention, grabbing device 128 can comprise that mechanical organ is such as horizontal clamper or Mobile support device (not shown), for interacting with near the plate 14 and/or 16 in their lateral edge or their lateral edge, with the movable support thing that captures or be formed in any case to make their raise or decline along edge gripper shoe and in the time operating, as mentioned above, in vacuum environment, plate is connected together carrying out.

Use various devices,

plate

14,16 can alternately be loaded on conveyer 124 (individually or in groups).Device 147 for application of adhesive can be disposed in the optional preferred some place along travel path.

As being clear that in Fig. 3, according to the embodiment of the present invention, equipment can comprise other induction system, advantageously comprises towards vacuum join domain 125 and transports plate, makes plate draw off in groups band and/or the roller path on the top of conveyer 124.

Advantageously, these other plate transportation systems form independent path, for preparing must connect together to form the first plate and second plate of panel.

Especially, in equipment, advantageously exist and be used for Preparation Example as the first area 145 of the first plate 14 of being made up of ceramic material, first area 145 comprises by the first known loading attachment 146 itself locates the first plate 14 for the first conveyer 144 thereon; And for Preparation Example as the second area 165 of the second plate 16 of being made by stone material, second area 165 comprises again advantageously locates the second plate 16 for second conveyor 164 thereon by the second loading attachment 166.

According to possible embodiment, the first conveyer 144 and second conveyor 164 can be formed by conveyer belt or roller path separately, as being end feed machine 124.

Advantageously, near the front end of conveyer 144,164 (if existed, especially near the first and second loading attachments 146,166), known baking oven (being preferably posture) can be set, if desired, for dry the first plate and/or the second plate 14,16.Obtain moisture free connecting surface with baking oven, the bonding strength of

plate

14,16 can adversely not affected.

Preferably, loading attachment (advantageously, suction cup manipulation device) 146 and 166 is placed on single plate on the front end of

corresponding conveyer

144 and 164.

Row's gripper shoe 14 on conveyer 144 is through adhesive dispensing device 147, and therefore the plate with the adhesive on the top surface that is arranged in them arrives the 148(of loading depot and advantageously comprises manipulation device), loading depot 148 shifts (displace) plate in groups, to be formed on the plate 14 of the adjacent row on conveyer 124.

Similarly, the row's plate 16 on conveyer 164 arrives the 168(of loading depot and advantageously comprises suction cup manipulation device), it is transfer blade in groups, to be formed on the adjacent row's that plate 14 on conveyer 124 and in groups alternately arranges plate 16.

The group of the order forming thus brings to join domain by conveyer 124, connects together, as above described to be arranged to one on another top and under vacuum.

Fig. 4 shows the schematic side elevation of a part for the equipment that comprises conveyer 124, is included in the possible preferred embodiment in the region in the downstream of bell-shaped element 126.

As noticed from Fig. 4, in the upstream of join domain 125, the second plate 18 and the first plate 14 that is provided with adhesive 18 are thereon placed with the order replacing by

manipulation device

148 and 168 respectively.In the embodiments of the present invention shown in Fig. 4, the region that conveyer 164 arrives together with transfer device 168 is positioned at the downstream in the region that conveyer 144 arrives together with transfer device 148, make by moving conveyor 124, first top plate 16 can enter join domain.

In the downstream of join domain 125, equipment can advantageously comprise known posture baking oven (as represented by reference number 140 in Fig. 4), for making the adhesive sclerosis of the panel forming.

Form panel if expected with three blocks of plates that connect together, as present those skilled in the art can easily expect, likely suitably operate equipment mentioned above, first to obtain the connection of two boards, then make the 3rd plate connect together with the two boards of beginning, or supplement/modification equipment.

For example, likely, first make as described above ground two boards connect together under vacuum condition, again open bell-shaped element, the two boards that rising has connected together, provides the 3rd plate with the adhesive being coated on top, and it is connected together with other two boards under vacuum, just as the latter is top plate, as described in above describe about the operation of independent two boards.

Along conventionally identical with plate 17 for feeding plate 16() line, the 3rd plate can be provided to join domain, is equivalent to the adhesive applicator of device 147 to equipment increase.Mainly, use conveyer 124, must one group of plate 16, one group of plate 14 with adhesive is identical with plate 16 with one group of plate 17(with adhesive) be supplied to join domain.

At this moment, how realizing predetermined object is clearly.By method and apparatus according to the invention, it is possible realizing best gummed.Due to making plate provide vacuum before connecting together, so the intensity of described vacuum is lower than (for example,, even lower than as many as 1/3rd) desired intensity in the prior art.Vacuum plant is in its production and to operate aspect both can be more simply and more cheap.And in the case of the plate raising in vacuum environment by suction cup, the suction force of suction cup can remain under lower vacuum values.

Owing to the method according to this invention, adhesive can have relatively low density, makes between compression period, and it easily produces the uniform layer for covering whole connecting surface.And, do not need onboard high pressure to come with uniform mode compression binder.The placement of adhesive be by adhesive compared with low-density and be that the more not crucial fact is carried out facilitation by the distribution of adhesive.For example, the form that adhesive can pearl is applied, described pearl near or there is not necessarily straight and/or parallel advancing (progression).

Finally, the speed of equipment can be larger than the speed of conventional equipment of removing air from the plate connecting, because the discharge of air can more easily and rapidly be carried out and can use lower vacuum.

Significantly, the above description of applying the embodiment of inventive concept of the present invention is to provide by the example of these inventive concept, and therefore should not be considered to the restriction scope of desired rights and interests herein.

For example, about embodiment mentioned above, in order to meet specific requirement, those skilled in the art can change described element and/or replace described element with IF-AND-ONLY-IF element, and does not therefore deviate from the scope of claims.

Claims

1. for the manufacture of an equipment for the goods of the form of composite panel (12), described composite panel (12) comprises at least the first plate (14) and the second plate (16) that are glued to together, and described equipment comprises:

Join domain (125), it is suitable for being maintained under vacuum; And

Manipulation device (128), it is suitable for making described plate (14,16) to connect together in the described join domain remaining under vacuum.

2. equipment according to claim 1, it is characterized in that, described join domain (125) comprises and is suitable for coordinating with the stayed surface (124) for described plate with by vacuum plant vacuum bell-shaped element (126) therein, described bell-shaped element (126) is suitable for raising and declining towards described stayed surface (124) from described stayed surface (124), to allow entering and leaving of plate.

3. equipment according to claim 1 and 2, it is characterized in that, described manipulation device (128) comprises and is arranged in being suitable for from described stayed surface (124) elevating board (14 for described plate in described bell-shaped element, 16) and by plate (14,16) be placed on for the device on the described stayed surface (124) of described plate.

4. according to the equipment described in last claim, it is characterized in that, described manipulation device (128) is suction cup device.

5. according to the equipment described in last claim, it is characterized in that, described suction cup device is the suction surface (129) that is connected to vacuum loop.

6. according to the equipment described in any one in claim 1 to 5, it is characterized in that, described join domain (125) is transferred machine (124) and passes, described conveyer (124) works as stayed surface, described the first plate (14) and described the second plate (16) with the positioned in sequence that replaces on described conveyer (124).

7. according to the equipment described in any one in claim 1 to 6, it is characterized in that, comprising:

First area (145), it is for preparing described the first plate (14), described first area (145) comprises the first conveyer (144) and station (147), it is upper that described the first plate (14) is positioned at described the first conveyer (144) by the first loading attachment (146), and described station (147) are for being applied to adhesive (18) on the surface of described the first plate (14);

Second area (165), it is for preparing the second plate (16), and described second area (165) comprises second conveyor (164), and it is upper that described the second plate (16) is positioned at described second conveyor (164) by the second loading attachment (166), and

The first conveyer and second conveyor, it is unloaded to described the first plate and described the second plate on the described conveyer (124) working as stayed surface using the order replacing by loading depot (148,168).

8. for the manufacture of a method for the goods of the form of composite panel (12), described composite panel (12) comprises at least the first plate (14) and second plate (16) of gummed each other, said method comprising the steps of:

Adhesive (18) is assigned at least one the side (141,161) in described the first plate and described the second plate (14,16);

Under the condition of separating, described plate (14,16) is placed in vacuum environment,

In described plate (14,16) is remained on to vacuum environment time, utilize described adhesive betwixt that described plate (14,16) is connected together, to form described composite panel (12); And

Described panel (12) is exposed to atmospheric pressure.

9. method according to claim 8, it is characterized in that, in order to form two panels, said method comprising the steps of: under vacuum condition, by the adhesive being arranged in therebetween, the 3rd plate (17) is connected to described the first plate or described the second plate, to form the panel of three blocks of plates that comprise intermediate plate (14), described panel is exposed to atmospheric pressure again and is then parallel to gummed side and cut described intermediate plate, to form two independent panels.

10. method according to claim 8 or claim 9, it is characterized in that, by described plate (14,16,17) step connecting together and described panel (12) is exposed between the step of atmospheric pressure, exists to apply to be suitable for making described plate (14,16,17) power being moved toward each other, the step of compression arrangement described adhesive betwixt.

Method in 11. according to Claim 8-10 described in any one, is characterized in that, distributes described adhesive to carry out under vacuum.

12. methods according to claim 8 or claim 9, is characterized in that, are included in the initial step of preparing described adhesive (18) under vacuum environment.

Method in 13. according to Claim 8-12 described in any one, is characterized in that, described adhesive (18) is assigned with to leave the region that there is no the surface of the described plate of adhesive (141,142) before described Connection Step.

Method in 14. according to Claim 8-13 described in any one, is characterized in that, described adhesive (18) is assigned with the form of pearl (20).

Method in 15. according to Claim 8-14 described in any one, is characterized in that, described vacuum have 80 and 120mbar between residual pressure.

Method in 16. according to Claim 8-15 described in any one, is characterized in that, is suitable for making power that described plate (14,16,17) is moved toward each other corresponding to being greater than 0.05N/cm ²pressure.

Method in 17. according to Claim 8-16 described in any one, it is characterized in that, described the first plate working as supporter (14) is made up of coalescence material or ceramic material, and described the second plate (16) working as coating is made up of natural stone material.

18. methods according to claim 9, is characterized in that, described the 3rd plate (17) is made up of ceramic material.