Using a CO2 Laser-Firing as a Clean Production Method to Form an Electrical Conductivity Surface and Color-Changing on Craft Ceramic.

Craft ceramic is an old industry. Most craft clay needs to be red in a kiln, but kilns are expensive and inecient [Kiln ring thermal eciency: Kiln body heat storage 18.67%, Exhaust Sensible Heat 45.9%, Heat loss from incomplete combustion 16.24%, Radiated Conduction and Other Loss of Heat 12.61%]. In order to change the color of ceramic, potters commonly use kiln reduction ring. This technique requires an additional step and more fuel, which creates more air pollution. In this study, we used a CO 2 laser to re craft clay and glaze. This process not only changes the ceramic’s color but also changes the conductivity of the ceramic’s surface. By changing the composition of the glaze, the ceramic’s surface resistance was altered. Most kiln-red ceramics are non-conductive because oxides are combined by covalent bonds. During the laser ring process, the covalent bonds become metal bonds. collect more ceramic

In the kiln ring process, a potter must control fuel and air to create an oxidizing or a reducing ring environment. This allows for a change in glaze color. Kiln ring is time-and resource-intensive. It requires an average of 8~168 hours to re ceramic because the thermal e ciency of most kilns is less than 3%.
In this experiment, we used a CO 2 laser to re clay and glaze. We then compared the nal products of the kiln ring and laser ring processes.
This article includes the following sections: 1. Kiln ring is a traditional ceramic manufacturing technology. The kiln reduction ring process uses fuel control to reduce metal-oxygen. In a kiln that is heated to 950°C~1300°C, the oxygen atoms in the oxidized metal are combined with carbon atoms so that the metal displays its original color. In the kiln reduction ring process, the kiln expels large quantities of smoke and heat.
2. By changing the coloring metal in the glazes that we used, we achieved the results of ceramics reduction ring techniques while using laser ring.
Laser reduction ring creates no air pollution, requires no kiln equipment, and is less time-intensive than kiln ring.
3. Using the laser ring technique detailed in our patent (Taiwan, R.O.C Patent Number: I687394), we were able to create an electrically conductive surface on craft ceramic.  3 and CuCo 3 are non-conductive ceramic metal colorants. A typical ceramic glaze component usually contains 0.5%-12% of these colorants. In kiln oxidation ring, the addition of 0.5% to 12% Fe 2 O 3 changes the glaze color from light yellow to black. In kiln reduction ring, the addition of 0.5% to 12% Fe 2 O 3 changes the glaze color from light green to black.

Reduction Firing
In a kiln with a temperature between 900°C~1300°C, insu cient air for the amount of fuel creates an "incomplete ring". The technique of incomplete ring is used to change glaze color.
High temperatures are required to convert a kiln's fuel [solid or liquid] to gas. As the temperature becomes higher, the fuel conversion becomes faster. To achieve reduction ring, the fuel and air levels in a kiln must be controllable.
In wood-red kilns, these temperatures (900 ~ 1300 °C) are required for changing the glaze color.
In the reduction ring process, the oxidized metal in the ceramic body and the glaze is changed to an unoxidized metal. This changes the ceramic's surface color.
Hydrogen, carbon, and CO combine with oxygen, and the incomplete combustion gas steals oxygen from the glaze and the ceramic bodies. ( Tony Hansen, 2015) This reduction ring step requires heavy wood burning, the byproducts of which include heavy smoke and ash.
Therefore, kiln reduction ring is a major contributor to the ceramic industry's pollution problem.
Copper red glaze, reduction ring, and kiln ring skills.
When kiln temperatures are high and ceramics are processed in an alternating cycle of reduction and oxidation ring, copper glazes display excellent reds and heat into colloidal copper metallic.
In oxidation ring, copper glazes display a green color. In reduction ring, however, they displays a red or black color. Ceramic reduction ring needs over 5~8 hours to work, and it expels pollutants like smoke and incomplete ring gases.
For workers in ceramic factories, reduction ring may lead to permanent health problems like lung damage and respiratory disease.
2.2. Re tting the CO 2 laser to re craft ceramic.
The existing laser technology for ceramic ring is not yet perfect. Remaining challenges include the e cient production of lasers on a large scale and the development of high-power lasers and stable laser operations. (Akio Ikesue, Yan Lin Aung, 2008). New CO 2 laser technology could improve the economics and convenience of ceramics processing. The convenience and cost-effectiveness of these new lasers could make laser ceramic processing a mainstream technique. CO 2 lasers emit in the FIR at a wavelength of 10.6 microns, which is easily absorbed by most ceramics. They also have high output powers, which allow for high-speed processing and the processing of thick materials. ( BAJRANG LAL,2013) The laser used in our study has two ring types: cutting and engraving.
The laser focal length ranges from 0 to 60mm. To reduce variables, we set our laser power to 20W.
For record a broader range of data, we experimented with defocused ring and/or removed the laser lens.
Laser cutting can quickly quickly create a " ring" effect on a ceramic surface. It also quickly displayed a heating resul on the cermaict.
Laser Engraving: [surface at cutting] 2) Laser setting: power at 5~50W, speed at 1~300 mm/sec. The non-focal length is 0~40mm. The engraving spacing 0.5~0.1mm After using laser engraving settings, we observed a at ceramic area with glass on its surface.
In order to reduce testing time, we rst did full-range cutting (1~300 sec/mm) on the testing area.
In this way, we found the lowest effective power range. We then tested the defocused ring in the second step.
When performing laser cutting on a tile, we found that adjusting the laser's air blowing power affected the vitri ed [glass] substance on the ceramic's surface.
Each laser has an air-blowing feature, which is a protective function that prevents the lens from smoking.
Laser ring makes ceramics liquefy rapidly and expand. During the laser ring, if the air-blowing function is too strong, the liquid ceramic will be blown away.
To prevent this problem, we adjusted the laser's air blowing pressure. We found that heavy air blowing made an etching effect, while light air blowing created glaze vitri cation and welding effects.
Firing the same glaze with a laser and a kiln creates a very different physical reaction. The laser ring rate is more than 10,000 times faster than kiln ring.

Basic CO 2 laser formula
Using the following formula, we measured the laser's diameter in millimeters and calculated its power density.
The laser's light diameter is 2mm, the lens focus point diameter is 0.2mm, and the focal length is 20mm. When the focal length is over 40 mm, the laser's point diameter is 2mm.

Craft ceramic and Laser 3D modeling
According to the above re t, we started ring the craft clay using a 20W laser.
Using a layered laser-ring method, we were able to achieve clay melt at a depth of about 2mm.
We cut the clay into a thin slice , and then added one new slice of clay on top of the already-red layer. After completing several of these laser-ring processes, we cleaned the clay sample with water. After washing the clay, we were able to observe a vitri ed [glass] tube in the clay. This observation con rmed that craft clay can be used in laser 3D modeling. A Kiln ring system requires a lot of equipment, like a kiln, a gas tank, an electrical system, and a chimney. Because laser ring systems can be operated without kiln equipment and fossil fuels, they are much more cost-e cient.

Comparing kiln ring and laser-ring processes for ceramic
To test laser ring's ability to infer corresponding kiln temperatures, we changed the clay and used a kiln ring tool (Orton Cone 014, Temperature cone).
The following table shows our results: Comparing kiln ring and laser ring We red clay and glaze with a 20W laser at 1~20mm/sec.
Building off of observations from our kiln ring experience, we changed several glaze elements and observed the corresponding laser ring results.
After changing the laser speed and the ceramic component, we observed a melting effect on ceramic that was red via laser. Each element of the ceramic had a different melting temperature and heating rate.
As shown in the Orton Cone 014 ring temperature chart, the kiln heating rate is 30°C/hr. In other words, in kiln ring, energy accumulation is based on the kiln's heating rate. When enough energy is accumulated, the Orton Cone will melt or bend.
We used the laser to re ceramic and the Orton Cone. The laser speed corresponded to the kiln's ring temperature. With different laser speeds, the energy accumulation created a bending [wave] texture on the ceramic and the Orton Cone.
In our tests, the laser's speed had a bigger impact on the nal product than the laser's power did.
By using a lens to concentrate the laser on a 0.2mm focus point, we achieved a rapid heating effect.
Based on the melting speed we observed in the ceramic, the laser's heating rate is much higher than the heating rate of the kiln.
In the ceramic vitri cation ring process, the kiln heated at a rate of 0.0416 °C/sec. The laser heated at a rate of 527.85°C /sec. The laser's heating rate is 12688.7 times faster than the kiln's heating rate. According to these ring tests, kiln ring and laser ring create different results in the nal ceramic product.
In laser heating, the glaze's melting pattern is different than it is in kiln ring. To gure out the differences between these two techniques, we compared ceramics red by kiln with laser-red ceramics. By recording the melting pattern of the ceramic surface and the laser speed, we found that the laser has a comparatively high heating rate.
When we set the laser's speed to 1mm~20mm/sec, we observed the following features: According to kiln ring classi cations, ceramic products are divided into blanks (body) and glazes.
The ceramic body's melting temperature must be higher than the glaze by over 100°C. This temperature discrepancy allows the product to maintain its shape and form a smoothly-textured glaze on its surface.
1. In this study, we used a laser (20W, 1~20 mm/sec) to re ceramic materials. The Iron oxide in the clay showed a reduction color when laser-red as it did in kiln reduction rings.
2. We also used the laser to re the same clay at different temperatures. We studied 1) room temperature clay, 2) clay red at 800 °C, and 3) clay red at 1230°C. At each temperature, the result when red at a slow laser speed (1~2 mm/sec) was the same. From this we conclude that the result of laser-ring is similar to that of kiln ring. In this way, we can measure the craft clay and the glaze's heat resistance.
3. When we changed the laser speed, the clay surface displayed a gradual change in texture. By recording the gradual change in texture, we observed the melting threshold of the clay.
At the same laser speed, an obvious wavy texture [a "melt & ow" texture] appeared on the ceramic surface of the clay at room temperature, the clay red at 800 °C, and the clay red at 1230 °C.
When compared, the kiln-red and the laser-red glaze and clay displayed different features.
The laser's high heating rate made the glaze's melt different than the kiln-red melt.
With the laser's speed set to 1mm~20mm/sec, we red the ceramic and recorded its surface melt.
1. When a 20W laser was used, the clay displayed a green color. When kiln red, it displayed a brown color.
Our clay contains 2.3% iron oxide. Based on this percentage, we predicted that the iron oxide colorants would cause the clay color to change. We also predicted that the glaze's components would affect the laser ring result.
2. We observed an obvious wavy texture and melting texture on both the clay and the glaze when they were red with lasers of different speeds at several different ranges.
3. When ring ceramic in a kiln, a potter adds clinker powder into the clay to reduce clay shrinkage.
For the above reasons, we believe that the obvious wavy texture and melting texture on the laser-red ceramics are due to a difference in shrinkage rate. Each glaze has its own melting temperature.
For this reason, the obvious wavy texture appears on the surface of different ceramics with different glaze components that are red at different laser speeds.
In our test samples (kiln ring with blanks bodies sintering at 1230°C and glazes melting at 1230°C), the blanks bodies (kiln red at 1230°C, sintered) displayed an obvious wavy texture when laser red at 5 mm/sec.
The glazes (kiln red at 1230°C, melted) displayed an obvious wavy texture when red with a laser at 14 mm/sec.

Laser energy calculation and kiln ring comparison
In this test, we used 20W lasers at several different speeds. We then plugged our results into the following equation: Power Density/ speed (mm/sec) = Ceramic ring energy value The laser's focal point radius was set to 0.2mm, and the laser's speed ranged from 1~20 mm/sec. According to data on kiln ring, ceramic products need a 250°C difference between blank (body) ring temperature and glaze ring temperature.
By calculating the energy and sample melting data of a 20W laser with a speed of 3~10 mm/sec, we were able to mimic the results of kiln ring at 1240~1000°C.
The laser's ring energy rapidly attenuated as the laser's speed increased. A low laser speed can therefore accurately predict the kiln ring temperature needed for a given piece of ceramic.

Using laser ring to form a reduction ceramic surface.
Laser ring is able to change the color of ceramic. To identify the reason for this, we conducted a ring test that compared glaze component changes in both kiln ring and laser ring. We studied a clay with 2.33% Fe 2 O 3 and used glaze elements to form a clay-like component without Fe 2 O 3 . The laser ring melting energy was the same for both components.
We found that : 1)The clay containing 2.33% Fe 2 O 3 displayed a green color when laser red.
2)The glaze containing 0% Fe 2 O 3 displayed a transparent color when laser red.
3)The clay containing 2.33% Fe 2 O 3 displayed a brown color when red via kiln oxidation.
4)The glaze containing 3% Cu 2 CO 3 displayed a green color when kiln red.
5)The glaze containing 3% Cu 2 CO 3 displayed a red color when laser red.
Based on these observations, we concluded that laser ring can form a reduction ring effect in an oxidized environment. Using the data from this ring test, we obtained an invention patent [Taiwan, R.O.C Patent Number: I687394].
3.5 Laser ring Fe 2 O 3 and the CuCO 3 to from a conductive ceramicsurface According to the above laser ring test, laser ring can create a reduction ring effect on ceramic. Our next test uses laser reduction ring to make oxidized metal conductive.
We began with non-conductive oxidized metals Fe 2 O 3 and CuCO 3 . We then used a laser to re those oxidized metals.
After being laser red, they became conductive but were very fragile.
We tried ring the oxidized metals again, this time on a ceramic surface. After ring and cleaning the surface, we achieved a conductive metal surface [CuCO 3 with 42Ω and Fe 2 O 3 with 120Ω].

Results & Suggestions
A 20W laser that is red at 10 mm/sec with a spacing of 1 mm is able to melt clay. Clay can easily absorb laser energy, which is due in part to its moisture content.
Wet clay [with less than 3% moisture content] is suitable for small-scale laser ring.
Using a multi-layered laser ring process, we created a ceramic ring. We used water cleaning methods to remove the ring from the surrounding material. Due to the effects of stress on the materials, the ceramic ring was not solid. This could be changed with improvements in 3D ceramic modeling.
The laser ring process creates results that are similar to those of the kiln reduction ring process. It also improves on the kiln ring process in several ways: 1) It allows for more precise control over oxidation and reduction ring areas on ceramics, 2) It requires a comparatively short ring time [the laser ring process is 99% faster than kiln ring], 3) There is no associated air pollution [100% reduction as compared to kiln ring], 4) It is possible to form a precise reduction ring area, 5) There are no expensive kiln costs [80% reduction in costs], 6) There is no complex training required to achieve reduction ring [99% less labor required as opposed to large-scale kiln ring].
A kiln takes over 22 hours to re ceramic products. We can reduce the ring time to just 5 minutes by using laser ring.

Results
Variables of the laser ring process include 1) power, 2) speed, 3) focal length, 4) spacing and 5) volume of air ow.
1. The laser's speed setting is usually higher than the power setting. At slow speeds, the clay melts better than it does under a high-powered laser. High power settings cause clay molecules to swell too quickly. This causes a failed ring and a melting, magma-like ceramic. For this reason, we tend to use low power settings when ring ceramic.
A defocused laser causes the laser light to overlap on the ceramic surface. A lens focal length between 20~40mm causes low energy accumulation.
Page 10/18 2. To maintain steady laser output, keep the laser lens clean, and prevent smoking, most laser machines have an airblowing function. We controlled the air pressure levels in our study by creating a switch for the air-blowing tube, which is located next to the laser lens. We found that high air pressure blows away the liquid ceramic and forms an etched area.
With low air pressure, the liquid ceramic is able to stay on the ceramic surface. By controlling the air expelled by the laser, we can potentially achieve laser printing, cutting, ring, and surface treatment on craft ceramic.
3. Craft clay melts well when red with a 20W laser at 10~2 mm/sec with a spacing of 1 mm. After using laser ring, it is easy to pick out the craft clay works by water cleaning the nal product and surrounding materials.
4. The moisture content of red clay absorbs a lot of the laser's energy. Water-heavy clay leads to small melting areas or complete failure to melt. On the other hand, a 20W laser with a speed of 10 mm/sec can create cracks when red at glass. This is because the relatively high energy creates stress on the glass's surface. When laser power is decreased to 10W and the speed is set to 10 mm/sec, the laser can be used for glass cutting.
5. In this study, laser ring achieves results that are similar to those of kiln reduction ring. Using laser ring, we can make a ceramic surface on which oxidation and reduction nishes coexist on the same ring area.
Laser ring is also free of many of kiln ring's shortcomings. These include 1) long ring times, 2) large amounts of air pollution associated with reduction ring, 3) unpredictable reduction ring results on ceramic, 4) Expensive kiln costs, and 5) the need for a specialized workforce. Kilns also take more than 22 hours to re a complete ceramic product. With laser ring, what once took hours now takes just a few minutes.
. Most kiln-red ceramics are non-conductive. Oxides are combined by covalent bonds, and with laser-ring, the covalent bonds become metal bonds. This means that laser ring can produce ceramic products that are superior in terms of light, heat, magnetism, and electricity.

Suggestions
In this study, we used 20W lasers to re craft ceramic. These lasers are low-power and easily accessible. The materials we tested include 1) Taiwan Miaoli clay, 2) kaolin clay, 3) glass, 4) tiles, 5) glaze, and more.
We found that ceramics with large molecular gaps can withstand more laser heating stress.
The 20W Laser can be used to cut wood and re ceramics.
As the 100W laser machine's price goes down, it is becoming more popular in primary schools in Taiwan. These lasers not only cut plywood but can also re ceramic and be used in science education. With adequate course planning and teacher training, these lasers could be an interesting addition to primary school curriculum.
To complete ceramic ring in a kiln, you need over 22 hours. Throughout this energy-intensive process, only 3.5% of the energy in the kiln is directly used to re the ceramic. On the other hand, laser ring can melt clay in less than 5 minutes without a kiln or other related equipment. The total cost of laser ring is more than 80% cheaper than kiln ring.
Using a 20W laser at 2~5 mm/sec, a 3% CuCO 3 glaze did not display a clear red color. When re red at 1 mm/sec, however, the glaze displayed a clear red color. We changed the glaze component to 100% CuCO 3 and red it on a ceramic surface. With a 20W laser and a speed of 5 mm/sec, the ceramic displayed a red color and adequate melting.
The laser ring time is much shorter than the ring time needed for the reduction step in a kiln. The laser requires 1/72 the amount of time that the kiln does.

conclusions
Laser ring is a promising new ceramic ring technique. We have 25 years of experience with kiln ring, including kilnbuilding, kiln ring skills, and expertise on ceramic glazes. In Taiwan, we also published a paper about how to construct a kiln that will reduce energy waste, recycle heat, and reduce air pollution.
The following is a quick introduction: " We made changes to the kiln ring process in order to reduce heat waste and conserve heat energy. In our design plan, excess heat is used to heat the water circulation system, and the hot water is used in an arti cial hot spring for power generation. In this way, we hope to promote the ceramic leisure industry and add to ceramic's industry value. Waste wood has many impurities, so choosing an absorbent that can absorb pollutants is important. Water is a good absorbent for many types of pollutants. In the ue, we installed a spray washing system to reduce ash pollution. This system sprays water into the chimney ue. In the ue, water droplets and exhaust gas trap ash particles in water droplets. With these water droplets, we use the diffusion mechanism and remove pollutants." Based on our observations, we believe that laser ring is a breakthrough innovation for craft ceramic production.

Cleaner production
Traditional kiln ring wastes over 75% of the energy involved in the ring process. It also requires worker training for specialized skills like process control and waste utilization. (Yi Huangac, Jiwen Luo, BinXiaa, 2013) This ine ciency is enough to necessitate change in mainstream ceramic production methods. Laser ring poses none of the environmental or economic challenges that come with kiln ring. Laser ring can create the effect of reduced ring without the oxygen required for kiln ring. This makes laser ring a cleaner alternative for mainstream ceramic production.

Sustainability & Environmental concerns
Making conductive ceramics in a kiln is time-intensive. It requires cutting, welding, and gluing a piece of conductive ceramic to create a new piece with electrical function. Using laser-ring, we simply placed ceramic elements on different layers throughout the ring process. This created an electrically functional ceramic piece. In this way, laser ring reduces production costs and lessens the environmental impact associated with the reduction process.
Laser ring not only reduces kiln ring times and costs but also prevents air pollution. Via laser ring, we can get ceramic ring data quickly and cheaply.
Each ceramic element has its own ring traits, and these traits in turn change the glaze traits in the nal ceramic piece. For this reason, we recommend that researchers continue exploring laser ring techniques.   Comparative map of ceramic melting point, laser ring energy, and kiln ring temperature.

Figure 6
Laser-ring energy map comparing ceramic melting temperatures with different kiln-red glaze formulas.