Patent Application
20120114860
The present invention generally relates to a manufacturing system including an electrode and a method of inhibiting formation of deposits on the electrode. More specifically, the present invention relates to a manufacturing system including an electrode that is used for depositing a material on a carrier body and that is cooled with a coolant composition, and a method of inhibiting formation of deposits on the electrode as a result of contact between the electrode and the coolant composition.
Methods for depositing a material on a carrier body are known in the art. One such method uses a manufacturing system, which includes a reactor defining a chamber. An electrode is disposed within the chamber for supporting the carrier body within the chamber. Typically, the electrode comprises a highly conductive material, such as copper. The manufacturing system also includes a power supply coupled to the electrode for providing an electric current to the electrode such that electric current passes through the electrode and into the carrier body. The passage of the electric current generates heat within the electrode and heats the carrier body to a deposition temperature.
A reactive gas and a precursor comprising the material are introduced into the chamber. Once the carrier body reaches the deposition temperature, the precursor reacts with the reactive gas resulting in the depositing of the material on the carrier body. However, the material will also be deposited onto the electrode if the electrode reaches the deposition temperature. Thus, it is desirable to prevent the electrode from reaching the deposition temperature while still enabling the carrier body to reach the deposition temperature.
There are several known methods for preventing the electrode from reaching the deposition temperature. In one embodiment, the electrode has a cooling surface and a coolant composition is provided for contacting the cooling surface to dissipate heat generated within the electrode. The contact between the coolant composition and the cooling surface of the electrode results in the formation of undesirable deposits on the cooling surface. The deposits decrease the rate of heat transfer between the coolant composition and the electrode.
It has been observed that the formation of the deposits on the electrode may depend on the type of coolant composition used. For example when the coolant composition is tap water, minerals can be suspended in the tap water and are deposited on the cooling surface. An attempted solution to the problems associated with the use of tap water as the coolant composition has been the use of deionized water, which lacks suspended minerals in the coolant composition. However, the use of deionized water yields only a slight delay in the formation of deposits on the electrode.
A fouling of the electrode occurs once the formation of deposits on the cooling surface are so extensive that the coolant composition cannot prevent the electrode from reaching the deposition temperature and the material becomes deposited on the electrode. Once fouling of the electrode occurs, the electrode must be replaced, which adds to production costs. Generally, the electrode has a life determined by the number of the carrier bodies the electrode can process before the electrode must be replaced. Additionally, once fouling and replacement of the electrode occurs, the coolant composition must also be replaced, further adding to the production costs.
It is to be appreciated that in the art of power generation, coolant compositions are also used to dissipate heat. In power generation, minerals in the coolant composition can increase the electrical conductivity of the coolant composition, resulting in damage to power generation equipment and a reduction in efficiency due to the highly sensitive nature of the power generation equipment. Further, the power generation equipment handles high amounts of electricity, which makes containment of the electricity through maintaining electrical conductivity of the coolant composition very important for safety and efficiency purposes. Therefore, in power generation, the control of minerals in the coolant composition is critical for the reduction of the electrical conductivity of the coolant composition and steps have been taken to remove minerals in the coolant composition through numerous mechanisms.
Accordingly, it would be advantageous to further develop a method of inhibiting the formation of deposits on the cooling surface of the electrode.
A method of inhibiting formation of deposits on a cooling surface of an electrode used in a manufacturing system for depositing a material on a carrier body is disclosed. The manufacturing system includes at least one reactor defining a chamber. At least one electrode is at least partially disposed within the chamber for supporting the carrier body within the chamber and the cooling surface of the electrode comprises copper. The manufacturing system also includes a coolant composition comprising a coolant and dissolved copper. A circulation system is coupled to the electrode and contains the coolant composition for transporting the coolant composition to and from the cooling surface of the electrode. The system further includes a filtration system in fluid communication with the circulation system. The method comprises the steps of heating the electrode supporting the carrier body and contacting the cooling surface of the electrode with the coolant composition. The method also includes the steps of depositing the material on the carrier body supported by the electrode and filtering the coolant composition with the filtration system to remove at least a portion of the dissolved copper therefrom.
As a result of contact between the cooling composition and the cooling surface, that comprises copper, copper dissolves into the coolant composition. It has been discovered that the dissolved copper is primarily responsible for the formation of the deposits on the cooling surface. Thus, one advantage of filtering the coolant composition is that it is possible to inhibit the formation of the deposits on the cooling surface for allowing heat within the electrode to be dissipated, thereby delaying the fouling of the electrode. Delaying the fouling of the electrode extends the life and productivity of the electrode. Another advantage of filtering the coolant composition is that the filtering increases a life of the coolant composition. Increasing the life of the electrode and the coolant composition increases productivity of the manufacturing system and decreases production costs.
Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description, when considered in connection with the accompanying drawings wherein:
Referring to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, a manufacturing system 20 for depositing a material on a carrier body 22 is disclosed. In one exemplary embodiment described additionally below, the material is silicon. However, it is to be appreciated that other materials known in the art can be deposited on the carrier body 22 without deviating from the scope of the subject invention. When the material is silicon, the carrier body 22 is typically a silicon slim rod.
Referring to
A precursor, comprising the material, is used to transport the material into the chamber 26. In particular, the material is deposited on the carrier body 22 as a result of a reaction of the precursor and a reactive gas. The material deposited on the carrier body 22 is dependent on the type of precursor used.
As an example, when the precursor comprises a halosilane such as trichlorosilane, the trichlorosilane, which is itself a gas in this application, is reacted with a reactive gas such as hydrogen through thermal cracking and hydrogen reduction to produce silicon. The silicon is deposited on the carrier body 22 and may react with the silicon of the carrier body 22 to form polycrystalline silicon (where, for example, the carrier body 22 is the silicon slim rod as described above). In this embodiment, the material is further defined as silicon. However, it is to be appreciated that the precursor is not limited to a trichlorosilane and can comprise other compounds comprising silicon. For example, the precursor can comprise silicon tetrachloride and/or tribromosilane. Furthermore, it is to be appreciated that materials other than silicon or in addition to silicon can also be deposited on the carrier body 22, in which case other precursors may alternatively be used.
The precursor enters the chamber 26 through the inlet 28 and any unreacted precursor, reactive gas, and by-products of the reaction of the precursor and the reactive gas are exhausted from the chamber 26 through the outlet 30.
As shown in
In one embodiment, the carrier body 22 has a U-shaped configuration with a first end 32 and a second end 34 spaced from each other. When the carrier body 22 is U-shaped, two electrodes 36 are utilized such that each of the electrodes 36 receives one of the ends 32, 34 of the carrier body 22.
Although not required, a socket 40 is typically disposed between the carrier body 22 and the electrode 36 for allowing the carrier body 22 to be easily separated from the electrode 36 after the material has been deposited onto the carrier body 22. When the carrier body 22 is U-shaped, a pair of sockets 40 are used such one socket 40 is disposed on one of the ends 32, 34 of the carrier body 22 and another socket 40 is disposed on the other of the ends, 32, 34. It is to be appreciated by those skilled in the art that the method of connecting the carrier body 22 to the electrode 36 can vary depending on the type of electrode 36 used and the configuration of the carrier body 22 without departing from the scope of the instant invention.
Referring to
In one embodiment, the electrode 36 includes a head 48 disposed at the top end 46 of the shaft 42. The head 48 and the shaft 42 each have a diameter D1, D2, respectively. Typically, the diameter D1 of the head 48 is larger than the diameter D2 of the shaft 42. Due to the diameter D1 of the head 48 relative to the diameter D2 of the shaft 42, the carrier body 22 can be supported in the chamber 26. When present, the head 48 is disposed within the chamber 26 for receiving the carrier body 22.
The electrode 36 comprises an electrically conductive material having a minimum electrical conductivity at room temperature of about 44×106 Siemens/meter (S/m). In one embodiment, the electrode 36 comprises copper and the copper is typically present in an amount of from about 100% by weight based on the weight of the electrode 36. However, the electrode 36 can comprise other suitable materials meeting the minimum electrical conductivity, such as silver or gold.
The electrode 36 has a cooling surface 38 that is atmospherically isolated from the chamber 26 of the reactor 24. Atmospherically isolating the cooling surface 38 from the chamber 26 prevents the introduction of contaminates into the chamber 26 which can affect the depositing of the material onto the carrier body 22. In one embodiment, the cooling surface 38 defines a channel 50 within the electrode 36 and the bottom end 44 of the shaft 42 defines a hole 52 for accessing the channel 50. The channel 50 extends within the electrode 36 a distance D such that the distance D is less than a length L of the electrode 36. Said differently, the channel 50 does not extend completely through the electrode 36. In an alternatively contemplated embodiment, the cooling surface 38 is an exterior of the electrode 36.
The cooling surface 38 comprises copper. Typically, the copper is present in the cooling surface 38 an amount of about 100% by weight. One example of suitable copper for both the electrode 36 and the cooling surface 38 is oxygen-free electrolytic copper grade UNS 10100. The copper of the cooling surface 38 provides the cooling surface 38 with excellent heat transfer properties. When the electrode 36 and the cooling surface 38 each comprise copper, the cooling surface 38 can be integral to the electrode 36. However, the cooling surface 38 and the electrode 36 can comprise different types of copper, in which case the cooling surface 38 is not integral with the electrode. Furthermore, when the electrode 36 does not comprise copper as described above, the cooling surface 38 is not integral to the electrode 36. In such an example where the cooling surface 38 in not integral with the electrode 36, the cooling surface 38 may be disposed adjacent to the electrode 36 by any acceptable methods known, such as electroplating.
Referring back to
Referring to
Referring back to
The coolant composition 56 is typically present within the circulation system 58 in a total volume and passes through the circulation system 58. It is to be appreciated that the total volume of the coolant composition 56 present may be dependent upon various factors such as a surface area of the cooling surface 38 resulting in the total volume being different for different manufacturing systems 20. Typically, the coolant composition 56 is circulated through the circulation system 58 at a flow rate of less than about 4,300, more typically of from about 2,200 to 4,300 gallons per minute (GPM). A circulation cycle is defined by the passage of an amount of the coolant composition 56 through the pump 64 equal to the total volume of the coolant composition 56 present in the circulation system 58.
The coolant composition 56 comprises a coolant for dissipating heat within the electrode 36 through thermal conduction between the cooling surface 38 and the coolant composition 56. Preferably, the coolant is deionized water due to the absence of minerals in deionized water however; it is to be appreciated that the coolant may be other fluids used for thermal conduction such as antifreeze, or tap water. The coolant composition 56 may also comprise dissolved gasses because the circulation system 58 is typically open to the atmosphere, which allows oxygen and carbon dioxide from the atmosphere to dissolve into the coolant composition 56. Therefore, the coolant composition 56 may comprise dissolved oxygen and dissolved carbon dioxide. However, it is to be appreciated that the circulation system 58 may be isolated from the atmosphere to prevent dissolved gasses from entering the coolant composition 56. When the circulation system 58 is isolated from the atmosphere, air may become trapped within the filtration system 70. For example, air may become trapped when the electrode 36 is replaced or as the coolant composition 56 is added to the circulation system 58. It is to be appreciated that the electrode 36 may be fitted with a purge connection to eliminate air that may become trapped within the circulation system 58.
As a result of the contact between the coolant composition 56 and the cooling surface 38 of the electrode 36, there is a presence of dissolved copper within the coolant composition 56, in the form of cupric (Cu2+) ions. As such, after the coolant composition 56 contacts the cooling surface 38, the coolant composition 56 comprises the coolant and the dissolved copper. It is to be appreciated that the coolant composition 56 may contact other parts of the manufacturing system that comprise copper, including, but not limited to, the power supply 54 and other electrical components such as cables, which can also contribute to the presence of dissolved copper within the coolant composition 56. It is believed the dissolved copper is introduced into the coolant composition 56 as a result of a degradation of the cooling surface 38. It is further believed that the dissolved copper or Cu2+ ions react with the dissolved oxygen to form copper oxide CuO, which precipitates out of the coolant composition 56 to form a deposit on the cooling surface 38 of the electrode 36.
It is believed that the degradation of the cooling surface 38 is influenced by a pH of the coolant composition 56. The dissolved carbon dioxide in the coolant composition 56 forms bicarbonate (HCO3−) through an equilibrium reaction, which tends to lower the pH of the coolant composition 56. Therefore, the amount of the bicarbonate present in the coolant composition 56 can be determined as a function of the change in the pH of the coolant composition 56 and the total volume of the coolant composition 56 present in the circulation system 58.
It is believed that degradation of the cooling surface 38 occurs as the bicarbonate reacts with the copper of the cooling surface 38, resulting in the degradation of the cooling surface 38, and the presence of dissolved copper in the coolant composition 56. The dissolved copper is suspended in the coolant composition 56 and circulated through the circulation system 58, thereby resulting in the formation of the deposits on the cooling surface 38 of the electrode 36 as described above.
Without being bound by any particular theory, it is believed that controlling the amount of dissolved copper in the coolant composition 56 and the pH of the coolant composition 56 will inhibit the formation of deposits on the cooling surface 38 of the electrode 36. For example, it is believed that that the rate of deposit formation on the cooling surface 38 increases when a solubility limit of copper into the coolant composition 56 is reached and the pH is below 7.0. It is also believed that the rate of deposit formation on the cooling surface 38 increases as the concentration of dissolved copper in the cooling composition increases and the pH is above 7.0. It is also believed that inhibiting the formation of deposits on the electrode 36 can also be accomplished by controlling an amount of dissolved oxygen in the coolant composition 56 by using a deareation system that isolates the coolant composition 56 from the atmosphere thereby preventing the formation of copper oxide. In such a system, the presence of dissolve copper in the absence of dissolved oxygen does not result in the formation of deposits on the electrode 36. However, it is believed that generally it is more effective to control the amount of dissolved copper in the coolant composition 56 rather than using the deareation system.
Inhibiting the formation of the deposits extends a life of the electrode 36 and a life of the coolant composition 56, which decreases production costs because the electrode 36 and coolant composition are not required to be replaced as often. Additionally, the production time to deposit the material on the carrier body 22 is also decreased because replacement of electrodes 36 occurs less frequently, as compared to when the coolant composition 56 has a greater presence of dissolved copper. Furthermore, the reduction in deposit formation on the cooling surface 38 of the electrode 36 also has the added benefit of improving cooling within the chamber 26 of the reactor 24, which benefits the productivity and extends the life of the reactor 24. In particular, reduction in the formation of the deposits on the cooling surface 38 enables the electrode 36 to be cooled more efficiently and thereby draw heat from the chamber 26, which prevents the reactor 24 from operating at unnecessarily high temperatures.
As stated above, the presence of the bicarbonate in the coolant composition 56 lowers the pH of the coolant composition 56. Generally, the lower, or more acidic, the pH is, the faster the degradation of the cooling surface 38, resulting in higher concentrations of dissolved copper present in the coolant composition 56. It is believed that the degradation of the cooling surface 38 can be minimized by maximizing the pH of the coolant composition 56. Typically, the pH of the coolant composition 56 is above 7.0. However, as the pH of the coolant composition 56 becomes basic, there is an increase in an electrical conductivity of the coolant composition 56. High electrical conductivity can result in electrical arcing, which can damage the electrode 36. Generally, high electrical conductivity of the coolant composition 56 is not a large problem but may be monitored to protect the electrode 36. Typically, if the pH of the coolant composition 56 is above 9.5, the electrical conductivity is too high and may result in damage to the electrode 36. In view of the foregoing, the manufacturing system 20 employs a three-layer control strategy to inhibit the formation of the deposits on the electrode 36. Generally, a first layer of the three-layer control strategy includes a filtration system 70 for filtering the coolant composition 56 to remove at least a portion of the dissolve copper in the coolant composition 56. A second layer of the three-layer control strategy includes maintaining a desired pH of the coolant composition 56 to minimize the degradation of the cooling surface 38. A third layer of the three-layered control strategy includes maintaining a desired electrical conductivity of the coolant composition 56 to prevent electrical arching. One advantage of the three-layer control strategy is that it identifies and controls factors that influence deposit formation on the cooling surface 38. Controlling the factors that influence deposit formation maximizes the life of the electrode, which decreases costs and replacement downtime. It is to be appreciated that the three-layer control strategy can be automated or manually performed.
The filtration system 70 is in fluid communication with the circulation system 58 for removing the dissolved copper from the coolant composition 56. As described above, the dissolved copper in the coolant composition 56 results in the formation of the deposits on the cooling surface 38. More specifically, the amount of dissolved copper in the coolant composition 56 at the point of contact between the coolant composition 56 and the cooling surface 38 has the greatest impact on the formation of deposits on the cooling surface 38. Therefore, it is preferred to control the amount of dissolved copper in the coolant composition 56 adjacent to the cooling surface 38 of the electrode 36. Said differently, it is preferred to control the amount of dissolved copper in the coolant composition 56 prior to the coolant composition 56 coming into contact with the cooling surface 38. Typically, an average concentration of the dissolved copper present in the coolant composition 56 is less than about 100, more typically less than about 50, and most typically less than about 25 ppb. It is to be appreciated that the upper limit and the lower limit of the dissolve copper can be selected independent from one another. The filtration system 70 removes the dissolved copper from the coolant composition 56 such that the average concentration of the dissolved copper in the coolant composition 56 is within the acceptable ranges listed above. Without the filtration system 70 of this invention, the average concentration of the dissolved copper in the coolant composition 56 would exceed 1000 ppb.
Generally, as the pH of the coolant composition increases, the copper oxide precipitates out of solution and can be filtered from the coolant composition 56. It is to be appreciated that the filtration system 70 can also remove copper oxide from the coolant composition 56. Additionally, when the manufacturing system 20 employs the deareation system, the deareated system may include the filtration system 70 for removing dissolved copper from the coolant composition 56.
In one embodiment, the filtration system 70 includes a filtration branch 72 in fluid communication with the main branch 62, the filtration system 70, and the main storage tank 60. The filtration branch 72 comprises a plurality of structural elements suitable for transporting the coolant composition 56 such as pipes, tubes, conduits and the like. The filtration branch 72 allows maintenance to be performed on the filtration system 70 without shutting down the manufacturing system 20. It is to be appreciated that the filtration system 70 can be in fluid communication with the main branch 62, thereby eliminating the filtration branch 72 from the circulation system 58.
A filtration branch valve diverts a portion of the coolant composition 56 from the main branch 62 into the filtration branch 72 for passing a portion of the coolant composition 56 through the filtration system 70. Typically, the coolant composition 56 passes through the filtration branch 72 at less than about 20, and more typically of from about 6 to 10 GPM. The filtration branch 72 allows for treating a lower flow rate as compared to the flow in the main branch 62 while still effectively controlling the dissolved copper content of the total volume of the coolant composition 56. Additionally, treating the coolant composition 56 at the lower flow rate reduces an operating cost of the filtration system 70 because the life of the filtration system 70 is extended as less of the coolant composition 56 is filtered per circulation cycle as compared to providing the filtration system 70 on the main branch 62. It is to be appreciated that the flow rate of the coolant composition 56 within the filtration system 70 depends upon the average concentration of dissolved copper present in the coolant composition 56, the total volume of the coolant composition 56 present in the circulation system 58, and the effectiveness of the filtration system 70 to remove the dissolved copper.
In one embodiment shown in
The filtration system 70 may also includes at least one mixed bed filter 76 containing a mixed resin in fluid communication with the filtration branch 72. The mixed bed filter 76 removes the bicarbonate from the coolant composition 56 and, therefore, decreases the amount of basic substance that must be added to the coolant composition 56 to bring the pH within the acceptable rages set forth above. It is to be appreciated that any type of mixed resin know in the art may be used with the present invention. Typically, the mixed resin comprises a combination of cation and anion beads mixed together. Generally, the mixed bed filter 76 can also be used to remove minerals that might be suspended within the coolant composition 56. For example, when the coolant is tap water, the mixed bed filter 76 removes any minerals suspended in the tap water.
With reference to
The second layer of the three-layer control strategy typically maintains the pH of the coolant composition 56 of from about 7.0 to 9.5, and more preferably of from about 7.5 to 9.5 and most preferably of from about 7.5 to 9.5. In view of the pH ranges for the coolant composition, the amount of dissolved copper introduced into the coolant composition 56 over time is minimized. In view of the preferred pH ranges, the coolant composition 56 has an electrical conductivity preferably less than about 80, and more preferably of from about 10 to 80 micro-Seimens.
It is to be appreciated that the pH of the coolant composition 56 can be maintained by any method suitable for maintaining the pH of the coolant composition 56 known in the art. In one embodiment, a basic substance is added to the coolant composition 56 to counteract the effect of the bicarbonate on the pH of the coolant composition 56. It is to be appreciated that the basic substance may comprise any strong base, such as potassium hydroxide, sodium bicarbonate, and sodium hydroxide. It is also to be appreciated that a portion of the coolant composition 56 can be removed from the circulation system 58 and replaced with a fluid such that the replacement results in the pH of the coolant composition 56 being within the ranges described above. It is to be appreciated that the mixed bed filter 76 may be used in cooperation with the basic substance to control the pH of the coolant composition 56. In some instances, the mixed bed may be used in place of the addition of the basic substance altogether.
Referring still to
It is to be appreciated that the pH maintenance branch 66 can be located either upstream or downstream of the reactor 24. A basic substance storage tank 68 is in fluid communication with the pH maintenance branch 66 for storing the basic substance. The basic substance from the basic substance storage tank 68 is added to the coolant composition 56 within the pH maintenance branch 66, to effectively control the pH of the total volume of the coolant composition 56. It is to be appreciated that the amount of caustic solution added to the coolant composition 56, as well as the rate of addition, is dependent upon the amount of bicarbonate present in the coolant composition 56 and the desired pH of the coolant composition 56.
The pH of the coolant composition 56 within the main storage tank 60 can be tested to ensure the pH of the coolant composition 56 is within the preferable range. The rate of addition of the basic substance can be adjusted based on the test results of the pH of the coolant composition 56 in the main storage tank 60. However, because the range of pH of the coolant composition 56 has an upper limit controlled by the electrical conductivity, controlling the pH of the coolant composition 56 alone does not completely prevent degradation of the cooling surface 38 or remove the dissolved copper from the coolant composition 56.
Referring to
With reference to
It is to be appreciated that the dissolved oxygen present in the coolant composition 56 may be controlled by other suitable mechanisms and methods. For example, a sodium sulfite treatment may be used to chemically scavenge the dissolved oxygen. This scavenging may result in the formation of sulfate ions, which may be subsequently removed from the coolant composition 56.
It is also to be appreciated that the average concentration of the dissolved copper present in the coolant composition 56 may be controlled by other suitable methods. For example, corrosion inhibitors may be added to the coolant composition 56 for preventing degradation of the cooling surface 38. The corrosion inhibitors attach to the dissolved copper as a passivation layer and prevent the formation of copper oxide in the coolant composition 56. Additionally, a chelating agent may be added to the coolant composition 56 for reacting with the dissolved copper to prevent the formation of the copper-oxide,
A typical method of inhibiting formation of deposits on the cooling surface 38 of the electrode 36 used in the manufacturing system 20 for depositing the material on the carrier body 22 is described below. The method includes the steps of placing the carrier body 22 in contact with the electrode 36 within the chamber 26 and sealing the chamber 26. Subsequently, the step of heating the carrier body 22 and the electrode 36 is performed by passing the electric current generated by the power supply 54 through the electrode 36 and the carrier body 22. The method also includes the steps of introducing the precursor into the chamber 26 and depositing the material on the carrier body 22 once the carrier body 22 reaches the deposition temperature. In one embodiment, the step of depositing the material on the carrier body 22 is further defined as depositing silicon on the carrier body 22. Additionally, the step of depositing silicon on the carrier body 22 may result in the formation of polycrystalline silicon on the carrier body 22.
The method further includes the steps of contacting the cooling surface 38 of the electrode 36 with the coolant composition 56 to dissipate the heat within the electrode 36 and filtering the coolant composition 56 with the filtration system 70 to remove at least a portion of the dissolved copper therefrom. In one embodiment, the step of filtering the coolant composition 56 is further defined as passing the coolant composition through the filtration system 70 at less than about 20 GPM. The step of filtering the coolant composition 56 with the filtration system 70 removes the dissolved copper present in the coolant composition 56 entering the filtration system by the percentages indicated above.
In one embodiment, the filtration system 70 is the cationic bed filter 74 and the step of filtering the coolant composition 56 is further defined as passing as least a portion of the coolant composition through the cationic bed filter 74. In another embodiment, the filtration system 70 is the reverse osmosis processor 77 and the step of filtering the coolant composition 56 is further defined as passing as least a portion of the coolant composition through the reverse osmosis processor 77. The method may also include the step of removing at least a portion of the dissolved gasses from the coolant composition 56 using the degasifier 78.
The method may also include the steps of maintaining the pH of the coolant composition 56 and maintaining the electrical conductivity of the coolant composition 56 in the ranges listed above. It is to be appreciated that the step of maintaining the pH of the coolant composition 56 is further defined as adding a basic substance to the coolant composition 56. The processed carrier body 22 is then removed and a new carrier body 22 is placed in the manufacturing system 20.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings. The foregoing invention has been described in accordance with the relevant legal standards; thus, the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and do come within the scope of the invention.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US10/41961 | 7/14/2010 | WO | 00 | 1/12/2012 |
| Number | Date | Country | |
|---|---|---|---|
| 61225347 | Jul 2009 | US |
