CN107573019A - A kind of preparation method of pottery - Google Patents

Abstract

The invention belongs to porcelain field, and in particular to a kind of preparation method of pottery, including following preparation process：The raw material includes blank and glaze, and glaze is by this medicine, the red feldspar in Yushan, iron oxide, quartz, burn talcum, calcite, plant ash, cupric oxide, Copper Ores, fluorite, ox bone ash, sodium tripolyphosphate, sodium humate composition, walk is made by blank, biscuit is fired early stage of lighting a fire, and first to carrying out dropping force in kiln, warming temperature is carried out in kiln, start to boost, kiln temperature reduces pressure again after reaching 1200 DEG C, when kiln temperature reaches 1250 DEG C to being incubated in kiln；It is only fiery after being heated up in kiln；Liquefied gas kiln is cooled again and is incubated again；Cooled after insulation, when can kiln discharge, preparation method of the invention simultaneously in set about from porcelain formula and burning process, the glaze changing effect got well, the preparation method of pottery of the present invention is reasonable, by having good glaze changing effect to the improvement pottery of formula and burning process.

Description

A kind of preparation method of pottery

Technical field

The invention belongs to porcelain field, and in particular to a kind of preparation method of pottery.

Background technology

Yuzhou of Henan god's Hou tradition chun glaze formula is fairly simple, as time goes on, making formula gradually diversified, how to change Good traditional chun glaze make it that transmutation effect is more rich and varied than traditional glaze U.S., while improves some performances of blank, while Under Environmental Protection Situation, the main flow for being fired into refreshing Hou potterys of liquefied gas kiln, but be to heat up too soon the shortcomings that liquefaction, for example used bavin in the past Coal firing is ceased fire with 20 several hours, 9 to 10 hour cans of liquefied gas, so causes firing time short, transmutation effect Fruit is general.How to extend the firing time of liquefied gas kiln is the very puzzled problem of current pottery people, therefore improves an ancient unit of weight from overall Porcelain prepare performance include formula and burning process so as to obtain transmutation effect, good pottery is that those skilled in the art urgently solve Certainly the problem of.

The content of the invention

The defects of based on prior art, it is an object of the invention to provide a kind of preparation method of pottery.

In order to achieve the above object, the present invention uses following technical scheme：A kind of preparation method of pottery, including following system Standby step：1）Raw material prepares：The raw material includes blank and glaze, and the blank is made up of the raw material of following parts by weight：Suzhou Kaolin 40-50 parts, wollastonite 3-5 parts, china clay 20-25 parts, feldspar 25-30 parts, medical stone 10-15 parts, camwood knag 5-10 parts, Bentonite 10-15 parts；The glaze is made up of the raw material of following parts by weight：This medicine 20-30 parts, the red feldspar 30-45 parts in Yushan, oxygen Change iron 3-4 parts, quartzy 5-10 parts, burn talcum 5-12 parts, calcite 10-15 parts, plant ash 3-5 parts, cupric oxide 1-2 parts, copper mine Stone 5-8 parts, fluorite 1-2 parts, ox bone ash 3-5 parts, sodium tripolyphosphate 0.05-0.08 parts, sodium humate 0.03-0.05 parts;

2）By step 1）In blank be made walk, first walk is placed on the wheel disc of rotation, embraced with hand just embracing it is suitable, then in mud A nest is deducted in the middle part on group top, and upper carrying handle nest lifts, then left hand is placed on inside nest, and the right hand is placed on outside nest, Two hands four refer to inside and outside with respect to pultrusion nest mud, are extended to top or outside, make the thinning base substrate into suitable thickness of nest mud, while make base Body turns into predetermined variously-shaped, and finally base substrate is cut off with a fine rule below the bottom of base substrate, then is revolved on runner Cut rest and reorganization；

3）Passing through step 2）The biscuit of not upper glaze, is put into temperature and fires 2-3h in 800 DEG C of -850 DEG C of kilns after finishing, element After burning, biscuit can once be picked again, underproof plain embryo is rejected；

4）By step 3）In qualified biscuit carry out glazing treatment：Lime-ash inside and outside biscuit is removed totally with instrument, uses sponge Dip in water and erase floating ash on biscuit, glazing, upper complete step 1 are carried out to biscuit）In glaze after carry out clear foot, glazed body foot bottom not The glaze needed is removed clean;

5）Biscuit after glazing is fired, comprised the following steps：

a）Biscuit after glazing is put into liquefied gas kiln, lighted a fire early stage, is first operated to carrying out dropping force in kiln so that pressure is 0.04MP；

b）By step a）In liquefied gas kiln in carry out warming temperature, start to boost when temperature reaches 950 DEG C, temperature from By pressure rise to 0.1MP in 950 DEG C to 1200 DEG C of temperature-rise period；

C) as step b）Middle liquefied gas kiln temperature reduces pressure to 0.01-0.03MP again after reaching 1200 DEG C；

d）When liquefied gas kiln temperature reaching 1200-1250 DEG C to carrying out being incubated 2-3 small in kiln；

e）Afterwards to step d）Carried out in middle liquefied gas kiln only fiery after being warming up to 1280-1300 DEG C；

f）Again liquefied gas kiln is carried out being cooled to 1000-1100 DEG C and be incubated 1-1.5h again；

g）Cooled after insulation, wicket can be slightly opened when dropping to below 200 DEG C makes its rapid cooling, at 100 DEG C or so Kiln discharge；

6）To the product after burning till, pick and classification are carried out according to pottery quality standard.

The preparation method of pottery of the present invention is reasonable, good by having to the improvement pottery of formula and burning process Glaze changing effect, ox bone ash are made of ox bone calcining, can be used as cosolvent, be made glaze paint gloss, promote liquid phase separation, plant ash master The elements such as calcium phosphorus are introduced, it is good cosolvent, there is certain suspension to glaze slip, the melting temperature and glaze of glaze can be reduced High temperature viscosity, while there is opaque and the facilitation to chun glaze split-phase, dosage should control, and pottery glaze changing effect is good, matches somebody with somebody Sodium tripolyphosphate has in side can play solubilization to glaze, and sodium humate is passed through by raw material of weathered coal, peat and lignite A kind of macromolecular organic monoacid sodium salt with multiple functions that special process is processed into, due to humic acid molecular weight itself It is larger, bigger particle can be also associated with certain medium, therefore there is colloid property and adsorption capacity, formed it is good from Son exchanges and catalytic action, preparation method mid-early stage pressure are put into minimum, is advantageous to the drying of base substrate, and rear fire is incubated favourable glaze paint Closing, improve the smoothness of chun glaze, make product transmutation effect more preferable, glaze paint is more gentle as beautiful, the overall control to pressure Increase is contributed to extend the firing time of liquefied gas kiln, so as to contribute to glaze to become.

Embodiment

The present invention is described in further details below by embodiment, embodiment is only used for illustrating the present invention, and unlimited The scope of the present invention processed.

Embodiment 1：A kind of preparation method of pottery, including following preparation process：1）Raw material prepares：The raw material includes base Material and glaze, the blank are made up of the raw material of following parts by weight：40 parts of Kaolin of Suzhou, 3 parts of wollastonite, 20 parts of china clay, length 25 parts of stone, 10 parts of medical stone, 5 parts of camwood knag, 10 parts of bentonite；The glaze is made up of the raw material of following parts by weight：This medicine 20 Part, 30 parts of the red feldspar in Yushan, 3 parts of iron oxide, 5 parts of quartz, burn 5 parts of talcum, 10 parts of calcite, 3 parts of plant ash, cupric oxide 1 Part, 5 parts of Copper Ores, 1 part of fluorite, 3 parts of ox bone ash, 0.05 part of sodium tripolyphosphate, 0.03 part of sodium humate;

2）By step 1）In blank be made walk, first walk is placed on the wheel disc of rotation, embraced with hand just embracing it is suitable, then in mud A nest is deducted in the middle part on group top, and upper carrying handle nest lifts, then left hand is placed on inside nest, and the right hand is placed on outside nest, Two hands four refer to inside and outside with respect to pultrusion nest mud, are extended to top or outside, make the thinning base substrate into suitable thickness of nest mud, while make base Body turns into predetermined variously-shaped, and finally base substrate is cut off with a fine rule below the bottom of base substrate, then is revolved on runner Cut rest and reorganization；

3）Passing through step 2）The biscuit of not upper glaze, is put into temperature and fires 2-3h in 800 DEG C of -850 DEG C of kilns, pass through after finishing Cross biscuiting, the organic matter in base substrate is oxidized, and moisture effusion, carbonate and sulfate therein are also decomposed, to can during glaze firing Avoid the volatilization of these materials and cause glaze paint the defects of pinhole, glaze bubble occur, while avoid the deposition of carbon, chun glaze can be made It is bright in colour, bright.Blank strength increase after biscuiting, beneficial to glazing, loading of kiln and transfer operation, can reduce breakage.Biscuiting Base substrate stomata increase afterwards, water absorbing force enhancing, improves sucking ability, easily reaches required glazed thickness during glazing, and It can guarantee that the processing quality requirement of glazing.Because the glaze layer of pottery is general thicker, without the base substrate of biscuiting, water absorbing force is low, warp The incessantly absorption of thick glaze, easily produces Blister after moulded pottery not yet put in a kiln to bake surface is drenched, glazing is also easy to peeling occur after burning till, lacks glaze etc. Problem.After biscuiting, biscuit can once be picked again, underproof plain embryo is rejected；Because some defects after biscuiting It is obvious, such as hidden crackle, pinhole, underproof biscuit is weeded out, can further improve the quality of pottery glaze firing finished product.

4）By step 3）In qualified biscuit carry out glazing treatment：Lime-ash inside and outside biscuit is clean with instrument removing, with Prevent occurring slag particle in glaze paint, influence glaze quality.Water is dipped in sponge and erases floating ash on biscuit, so that tire glaze combines after glazing Firmly, concentration refers to the dilute thick of glaze slip, and the thick concentration of glaze is big, and glaze dilute concentration is small, and glazing, upper complete step 1 are carried out to biscuit）In glaze Clear foot is carried out afterwards, the unwanted glaze of glazed body foot bottom is removed clean;

5）Biscuit after glazing is fired, comprised the following steps：

a）Biscuit after glazing is put into liquefied gas kiln, lighted a fire early stage, is first operated to carrying out dropping force in kiln so that pressure is 0.04MP；Pressure is put into minimum, is advantageous to the drying of base substrate,

b）By step a）In liquefied gas kiln in carry out warming temperature, start to boost when temperature reaches 950 DEG C, temperature from By pressure rise to 0.1MP in 950 DEG C to 1200 DEG C of temperature-rise period；

C) as step b）Middle liquefied gas kiln temperature reduces pressure to 0.01-0.03MP again after reaching 1200 DEG C；

d）When liquefied gas kiln temperature reaching 1200-1250 DEG C to carrying out being incubated 2-3 small in kiln；Fire is incubated favourable glaze afterwards The closing in face, the smoothness of chun glaze being improved, make product transmutation effect more preferable, glaze paint is more gentle as beautiful,

e）Afterwards to step d）Carried out in middle liquefied gas kiln only fiery after being warming up to 1280-1300 DEG C；

f）Again liquefied gas kiln is carried out being cooled to 1000-1100 DEG C and be incubated 1-1.5h again；

g）Cooled after insulation, wicket can be slightly opened when dropping to below 200 DEG C makes its rapid cooling, at 100 DEG C or so Kiln discharge.

6）To the product after burning till, pick and classification are carried out according to pottery quality standard.Certified products typically have certified products, essence Several ranks such as product, treasure.Certified products does not have defect or defect minimum, and transmutation effect is general；Fine work does not have any defect, has certain Transmutation effect；Treasure is then the outstanding person in fine work, and transmutation effect is abundant and unique.Transmutation effect includes pottery product glaze paint Color, spot, texture, hacking and natural picture, artistic conception etc..

Embodiment 2：A kind of preparation method of pottery, including following preparation process：1）Raw material prepares：The raw material includes base Material and glaze, the blank are made up of the raw material of following parts by weight：45 parts of Kaolin of Suzhou, 4 parts of wollastonite, 22 parts of china clay, length 28 parts of stone, 12 parts of medical stone, 8 parts of camwood knag, 12 parts of bentonite；The glaze is made up of the raw material of following parts by weight：This medicine 25 Part, 40 parts of the red feldspar in Yushan, 3 parts of iron oxide, 8 parts of quartz, burn 10 parts of talcum, 12 parts of calcite, 4 parts of plant ash, cupric oxide 1 Part, 7 parts of Copper Ores, 1 part of fluorite, 4 parts of ox bone ash, 0.06 part of sodium tripolyphosphate, 0.04 part of sodium humate;

2）By step 1）In blank be made walk, first walk is placed on the wheel disc of rotation, embraced with hand just embracing it is suitable, then in mud A nest is deducted in the middle part on group top, and upper carrying handle nest lifts, then left hand is placed on inside nest, and the right hand is placed on outside nest, Two hands four refer to inside and outside with respect to pultrusion nest mud, are extended to top or outside, make the thinning base substrate into suitable thickness of nest mud, while make base Body turns into predetermined variously-shaped, and finally base substrate is cut off with a fine rule below the bottom of base substrate, then is revolved on runner Cut rest and reorganization；

3）Passing through step 2）The biscuit of not upper glaze, is put into temperature and fires 2-3h in 800 DEG C of -850 DEG C of kilns, pass through after finishing Cross biscuiting, the organic matter in base substrate is oxidized, and moisture effusion, carbonate and sulfate therein are also decomposed, to can during glaze firing Avoid the volatilization of these materials and cause glaze paint the defects of pinhole, glaze bubble occur, while avoid the deposition of carbon, chun glaze can be made It is bright in colour, bright.Blank strength increase after biscuiting, beneficial to glazing, loading of kiln and transfer operation, can reduce breakage.Biscuiting Base substrate stomata increase afterwards, water absorbing force enhancing, improves sucking ability, easily reaches required glazed thickness during glazing, and It can guarantee that the processing quality requirement of glazing.Because the glaze layer of pottery is general thicker, without the base substrate of biscuiting, water absorbing force is low, warp The incessantly absorption of thick glaze, easily produces Blister after moulded pottery not yet put in a kiln to bake surface is drenched, glazing is also easy to peeling occur after burning till, lacks glaze etc. Problem.After biscuiting, biscuit can once be picked again, underproof plain embryo is rejected；Because some defects after biscuiting It is obvious, such as hidden crackle, pinhole, underproof biscuit is weeded out, can further improve the quality of pottery glaze firing finished product.

4）By step 3）In qualified biscuit carry out glazing treatment：Lime-ash inside and outside biscuit is clean with instrument removing, with Prevent occurring slag particle in glaze paint, influence glaze quality.Water is dipped in sponge and erases floating ash on biscuit, so that tire glaze combines after glazing Firmly, concentration refers to the dilute thick of glaze slip, and the thick concentration of glaze is big, and glaze dilute concentration is small, and glazing, upper complete step 1 are carried out to biscuit）In glaze Clear foot is carried out afterwards, the unwanted glaze of glazed body foot bottom is removed clean;

5）Biscuit after glazing is fired, comprised the following steps：

a）Biscuit after glazing is put into liquefied gas kiln, lighted a fire early stage, is first operated to carrying out dropping force in kiln so that pressure is 0.04MP；Pressure is put into minimum, is advantageous to the drying of base substrate,

b）By step a）In liquefied gas kiln in carry out warming temperature, start to boost when temperature reaches 950 DEG C, temperature from By pressure rise to 0.1MP in 950 DEG C to 1200 DEG C of temperature-rise period；

C) as step b）Middle liquefied gas kiln temperature reduces pressure to 0.01-0.03MP again after reaching 1200 DEG C；

d）When liquefied gas kiln temperature reaching 1200-1250 DEG C to carrying out being incubated 2-3 small in kiln；Fire is incubated favourable glaze afterwards The closing in face, the smoothness of chun glaze being improved, make product transmutation effect more preferable, glaze paint is more gentle as beautiful,

e）Afterwards to step d）Carried out in middle liquefied gas kiln only fiery after being warming up to 1280-1300 DEG C；

f）Again liquefied gas kiln is carried out being cooled to 1000-1100 DEG C and be incubated 1-1.5h again；

g）Cooled after insulation, wicket can be slightly opened when dropping to below 200 DEG C makes its rapid cooling, at 100 DEG C or so Kiln discharge.

6）To the product after burning till, pick and classification are carried out according to pottery quality standard.Certified products typically have certified products, essence Several ranks such as product, treasure.Certified products does not have defect or defect minimum, and transmutation effect is general；Fine work does not have any defect, has certain Transmutation effect；Treasure is then the outstanding person in fine work, and transmutation effect is abundant and unique.Transmutation effect includes pottery product glaze paint Color, spot, texture, hacking and natural picture, artistic conception etc..

Embodiment 3：A kind of preparation method of pottery, including following preparation process：1）Raw material prepares：The raw material includes base Material and glaze, the blank are made up of the raw material of following parts by weight：50 parts of Kaolin of Suzhou, 5 parts of wollastonite, 25 parts of china clay, length 30 parts of stone, 15 parts of medical stone, 10 parts of camwood knag, 15 parts of bentonite；The glaze is made up of the raw material of following parts by weight：This medicine 30 Part, 45 parts of the red feldspar in Yushan, 4 parts of iron oxide, 10 parts of quartz, burn 12 parts of talcum, 15 parts of calcite, 5 parts of plant ash, cupric oxide 2 parts, 8 parts of Copper Ores, 2 parts of fluorite, 5 parts of ox bone ash, 0.08 part of sodium tripolyphosphate, 0.05 part of sodium humate;

2）By step 1）In blank be made walk, first walk is placed on the wheel disc of rotation, embraced with hand just embracing it is suitable, then in mud A nest is deducted in the middle part on group top, and upper carrying handle nest lifts, then left hand is placed on inside nest, and the right hand is placed on outside nest, Two hands four refer to inside and outside with respect to pultrusion nest mud, are extended to top or outside, make the thinning base substrate into suitable thickness of nest mud, while make base Body turns into predetermined variously-shaped, and finally base substrate is cut off with a fine rule below the bottom of base substrate, then is revolved on runner Cut rest and reorganization；

3）Passing through step 2）The biscuit of not upper glaze, is put into temperature and fires 2-3h in 800 DEG C of -850 DEG C of kilns, pass through after finishing Cross biscuiting, the organic matter in base substrate is oxidized, and moisture effusion, carbonate and sulfate therein are also decomposed, to can during glaze firing Avoid the volatilization of these materials and cause glaze paint the defects of pinhole, glaze bubble occur, while avoid the deposition of carbon, chun glaze can be made It is bright in colour, bright.Blank strength increase after biscuiting, beneficial to glazing, loading of kiln and transfer operation, can reduce breakage.Biscuiting Base substrate stomata increase afterwards, water absorbing force enhancing, improves sucking ability, easily reaches required glazed thickness during glazing, and It can guarantee that the processing quality requirement of glazing.Because the glaze layer of pottery is general thicker, without the base substrate of biscuiting, water absorbing force is low, warp The incessantly absorption of thick glaze, easily produces Blister after moulded pottery not yet put in a kiln to bake surface is drenched, glazing is also easy to peeling occur after burning till, lacks glaze etc. Problem.After biscuiting, biscuit can once be picked again, underproof plain embryo is rejected；Because some defects after biscuiting It is obvious, such as hidden crackle, pinhole, underproof biscuit is weeded out, can further improve the quality of pottery glaze firing finished product.

4）By step 3）In qualified biscuit carry out glazing treatment：Lime-ash inside and outside biscuit is clean with instrument removing, with Prevent occurring slag particle in glaze paint, influence glaze quality.Water is dipped in sponge and erases floating ash on biscuit, so that tire glaze combines after glazing Firmly, concentration refers to the dilute thick of glaze slip, and the thick concentration of glaze is big, and glaze dilute concentration is small, and glazing, upper complete step 1 are carried out to biscuit）In glaze Clear foot is carried out afterwards, the unwanted glaze of glazed body foot bottom is removed clean;

5）Biscuit after glazing is fired, comprised the following steps：

a）Biscuit after glazing is put into liquefied gas kiln, lighted a fire early stage, is first operated to carrying out dropping force in kiln so that pressure is 0.04MP；Pressure is put into minimum, is advantageous to the drying of base substrate,

b）By step a）In liquefied gas kiln in carry out warming temperature, start to boost when temperature reaches 950 DEG C, temperature from By pressure rise to 0.1MP in 950 DEG C to 1200 DEG C of temperature-rise period；

C) as step b）Middle liquefied gas kiln temperature reduces pressure to 0.01-0.03MP again after reaching 1200 DEG C；

d）When liquefied gas kiln temperature reaching 1200-1250 DEG C to carrying out being incubated 2-3 small in kiln；Fire is incubated favourable glaze afterwards The closing in face, the smoothness of chun glaze being improved, make product transmutation effect more preferable, glaze paint is more gentle as beautiful,

e）Afterwards to step d）Carried out in middle liquefied gas kiln only fiery after being warming up to 1280-1300 DEG C；

f）Again liquefied gas kiln is carried out being cooled to 1000-1100 DEG C and be incubated 1-1.5h again；

g）Cooled after insulation, wicket can be slightly opened when dropping to below 200 DEG C makes its rapid cooling, at 100 DEG C or so Kiln discharge.

6）To the product after burning till, pick and classification are carried out according to pottery quality standard.Certified products typically have certified products, essence Several ranks such as product, treasure.Certified products does not have defect or defect minimum, and transmutation effect is general；Fine work does not have any defect, has certain Transmutation effect；Treasure is then the outstanding person in fine work, and transmutation effect is abundant and unique.Transmutation effect includes pottery product glaze paint Color, spot, texture, hacking and natural picture, artistic conception etc..

Claims (1)

1. a kind of preparation method of pottery, it is characterised in that including following preparation process：1）Raw material prepares：The raw material includes Blank and glaze, the blank are made up of the raw material of following parts by weight：Kaolin of Suzhou 40-50 parts, wollastonite 3-5 parts, china clay 20-25 parts, feldspar 25-30 parts, medical stone 10-15 parts, camwood knag 5-10 parts, bentonite 10-15 parts；The glaze is by following heavy Measure the raw material composition of part：This medicine 20-30 parts, the red feldspar 30-45 parts in Yushan, iron oxide 3-4 parts, quartzy 5-10 parts, burn talcum 5- 12 parts, calcite 10-15 parts, plant ash 3-5 parts, cupric oxide 1-2 parts, Copper Ores 5-8 parts, fluorite 1-2 parts, ox bone ash 3-5 Part, sodium tripolyphosphate 0.05-0.08 parts, sodium humate 0.03-0.05 parts;

2）By step 1）In blank be made walk, first walk is placed on the wheel disc of rotation, embraced with hand just embracing it is suitable, then in mud A nest is deducted in the middle part on group top, and upper carrying handle nest lifts, then left hand is placed on inside nest, and the right hand is placed on outside nest, Two hands four refer to inside and outside with respect to pultrusion nest mud, are extended to top or outside, make the thinning base substrate into suitable thickness of nest mud, while make base Body turns into predetermined variously-shaped, and finally base substrate is cut off with a fine rule below the bottom of base substrate, then is revolved on runner Cut rest and reorganization；

3）Passing through step 2）The biscuit of not upper glaze, is put into temperature and fires 2-3h in 800 DEG C of -850 DEG C of kilns after finishing, element After burning, biscuit can once be picked again, underproof plain embryo is rejected；

4）By step 3）In qualified biscuit carry out glazing treatment：Lime-ash inside and outside biscuit is removed totally with instrument, uses sponge Dip in water and erase floating ash on biscuit, glazing, upper complete step 1 are carried out to biscuit）In glaze after carry out clear foot, glazed body foot bottom not The glaze needed is removed clean;

5）Biscuit after glazing is fired, comprised the following steps：

a）Biscuit after glazing is put into liquefied gas kiln, lighted a fire early stage, is first operated to carrying out dropping force in kiln so that pressure is 0.04MP；

b）By step a）In liquefied gas kiln in carry out warming temperature, start to boost when temperature reaches 950 DEG C, temperature from By pressure rise to 0.1MP in 950 DEG C to 1200 DEG C of temperature-rise period；

C) as step b）Middle liquefied gas kiln temperature reduces pressure to 0.01-0.03MP again after reaching 1200 DEG C；

d）When liquefied gas kiln temperature reaching 1200-1250 DEG C to carrying out being incubated 2-3 small in kiln；

e）Afterwards to step d）Carried out in middle liquefied gas kiln only fiery after being warming up to 1280-1300 DEG C；

f）Again liquefied gas kiln is carried out being cooled to 1000-1100 DEG C and be incubated 1-1.5h again；

g）Cooled after insulation, wicket can be slightly opened when dropping to below 200 DEG C makes its rapid cooling, at 100 DEG C or so Kiln discharge；

6）To the product after burning till, pick and classification are carried out according to pottery quality standard.