As a liquid it can conform to the etched and porous structure of the anode and the grown oxide layer, and form a "tailor-made" cathode. BOX 161356 Mobile, AL 36616 [19][20] Otherwise, the electrolyte has to deliver the oxygen for self-healing processes, and water is the best chemical substance to do that.[18]. Inverters rely on capacitors to provide a smooth power output at varying levels of current; however electrolytic capacitors have a limited lifespan and age faster than dry components. The first reason for inverter failure is electro-mechanical wear on capacitors. In most cases, the effects of a low-energy surge aren’t severe. The Japanese manufacturer Rubycon became a leader in the development of new water-based electrolyte systems with enhanced conductivity in the late 1990s. . The thing with capacitor failure, is that it’s highly dependent on the type of capacitor, as well as the application it’s used in. Common values are 20 mfd and 40 mfd. The forming takes place whenever a positive voltage is applied to the anode, and generates an oxide layer whose thickness varies according to the applied voltage. Capacitors, especially large electrolytic capcitors in power supplies, do tend to fail over time, but it can take a very long time... Like, 10+ years (and in some cases decades longer). When capacitors are in use, energy surges and high temperatu… The new type of capacitor was called "Low-ESR" or "Low-Impedance", "Ultra-Low-Impedance" or "High-Ripple Current" series in the data sheets. Faulty ca­pac­i­tors have been a prob­lem since ca­pac­i­tors' ini­tial de­vel­op­ment, but the first flawed ca­pac­i­tors linked to Tai­wanese raw ma­te­r­ial prob­lems were re­ported by the spe­cial­ist mag­a­zine Pas­sive Com­po­nent Industry in Sep­tem­ber 2002.Shortly there­after, two main­stream elec­tron­ics jour­nals re­porte… This generates gas, which increases internal pressure. Under normal conditions the ESR has a very low value which stays that way for many years unless the rubber seal is defective, in which case the electrolyte’s water component gradually dries out and the ESR creeps up with time. The wear-out mechanism reaches a limit where devices will fall out of specification for the application. [19][20] The life of an electrolytic capacitor with defective electrolyte can be as little as two years. Try turning your system off and back on again, and if the problem persists, you’ll need to call in for professional help. He then took the faulty formula to the Luminous Town Electric company in China, where he had previously been employed. Aluminium electrolytic capacitors with non-solid electrolyte have grooves in the top of the case, forming a vent, which is designed to split open in the event of excessive gas pressure caused by heat, short circuit, or failing electrolyte. Capacitor casing sitting crooked on the circuit board, caused by the bottom rubber plug being pushed out, sometimes with electrolyte having leaked onto the motherboard from the base of the capacitor, visible as dark-brown or black surface deposits on the PCB. Modern electrolytic capacitors are based on the same fundamental design. These type of capacitors have high voltage and … This applies to most capacitors, but especially to aluminum. Anode surface with grown plaques of aluminium hydroxide, Anode surface with grown beads of aluminium hydroxide. But a failing capacitor may not show physical symptoms. The weak point remains and the anodic corrosion is ongoing. Continued operation of the capacitor can result in increased end termination resistance, additional heating, and eventual failure. Test equipment can diagnose failing capacitors. First is the electrolytic capacitor. This electrochemical behavior explains the self-healing mechanism of non-solid electrolytic capacitors. In electrolytic capacitors, the dielectric can crack in both low- and high-energy surges. So what is ESR and why would I need to know about that? There are lots of great web pages that include instructions on how to replace the aluminum electrolytic capacitors to repair the monitor. Vargel, M. Jacques, M. P. Schmidt, Corrosion of Aluminium, 2004 Elsevier B.V., Alfonso Berduque, Zongli Dou, Rong Xu, BHC Components Ltd (KEMET), Electrochemical Studies for Aluminium Electrolytic Capacitor Applications: Corrosion Analysis of Aluminium in Ethylene Glycol-Based Electrolytes. This issue has dominated the development of electrolytic capacitors over many decades. To protect the metallic aluminium against the aggressiveness of the water, some phosphate compounds, known as inhibitors or passivators, can be used to produce long-term stable capacitors with high-aqueous electrolytes. This led me to watch Dave Jones of eevblog.com fame discussion of electrolytic’s. Normally the anode foil is covered by the dielectric aluminium oxide (Al2O3) layer, which protects the base aluminium metal against the aggressiveness of aqueous alkali solutions. [25] First, a strongly exothermic reaction transforms metallic aluminium (Al) into aluminium hydroxide, Al(OH)3: This reaction is accelerated by a high electric field and by high temperatures, and is accompanied by a pressure buildup in the capacitor housing, caused by the released hydrogen gas. Domed tops 3. It can be more than 10 years for a 1000 h/105 °C capacitor operating at 40 °C. (The "vent" is stamped into the top of the casing of a can-shaped capacitor, forming a seam that is meant to split to relieve pressure build-up inside, preventing an explosion.). Electrolytic capacitors also have a self-healing ability, although to a lesser extent than film capacitors. Construction of a typical single-ended aluminium electrolytic capacitor with non-solid electrolyte, Closeup cross-section diagram of electrolytic capacitor, showing capacitor foils and oxide layers. Intermittent or outright failure Bad surface mount capacitors are not always easy to ide… The scientist then developed a copy of this electrolyte[citation needed]. Overheating is a primary cause of a failed start capacitor. ZL series capacitors with the new water-based electrolyte can attain an impedance of 23 mΩ with a ripple current of 1820 mA, an overall improvement of 30%. In a nutshell, they fail more often then not because of excessive temperature. The leakage current will increase to drive this self-healing effect. If the problem is in the centrifugal switch, thermal switch, or capacitor, the motor is usually serviced and repaired. Non-solid aluminium electrolytic capacitors without visible symptoms, which have improperly formulated electrolyte, typically show two electrical symptoms: When examining a failed electronic device, the failed capacitors can easily be recognized by clearly visible symptoms that include the following:[23], Failed Chhsi capacitor with crusty electrolyte buildup on the top, Failed capacitors next to CPU motherboard socket, Failed Tayeh capacitors which have vented subtly through their aluminium tops, Failed electrolytic capacitors with swollen can tops and expelled rubber seals, dates of manufacture "0106" and "0206" (June 2001 and June 2002), Failed capacitor has exploded and exposed internal elements, and another has partially blown off its casing, Failed Choyo capacitors (black color) which have leaked brownish electrolyte onto the motherboard. The electrolyte should also provide oxygen for the forming processes and self-healing. Capacitors react to energy surges in various ways. Temperature is of great concern to any capacitor. This diversity of requirements for the liquid electrolyte results in a broad variety of proprietary solutions, with thousands of patented electrolytes. Symptoms of electrolytic capacitor malfunction in radio and television are most often some form of audible noise, light or dark lines within the picture scan, or outright power supply failure. [8], Most of the affected capacitors were produced from 1999 to 2003 and failed between 2002 and 2005. What is Video TDR Failure? Run Capacitors A run capacitor is an energy-saving device that is in the motor circuit at all times. The non-solid aluminium electrolytic capacitors with improperly formulated electrolyte mostly belonged to the so-called "low equivalent series resistance (ESR)", "low impedance", or "high ripple current" e-cap series. For more on capacitors, visit http://www.electronicproducts.com/passives.asp. H. Kaesche, Die Korrosion der Metalle - Physikalisch-chemische Prinzipien und aktuelle Probleme, Springer-Verlag, Berlin, 1966, Chang, Jeng-Kuei, Liao, Chi-Min, Chen, Chih-Hsiung, Tsai, Wen-Ta, Effect of electrolyte composition on hydration resistance of anodized aluminium oxide, Learn how and when to remove this template message, Center for Advanced Life Cycle Engineering, "Low-ESR Aluminium Electrolytic Failures Linked to Taiwanese Raw Material Problems", The Capacitor Plague, Posted on 26 November 2010 by PC Tools, "Faults & Failures: Leaking capacitors muck up motherboards", "Taiwanese component problems may cause mass recalls", Capacitor failures plague motherboard vendors, GEEK, 7 February 2003, "Mainboardhersteller steht für Elko-Ausfall gerade", Michael Singer, CNET News, PCs plagued by bad capacitors, "Suit Over Faulty Computers Highlights Dell's Decline", "Taiwanese Cap Makers Deny Responsibility", "Capacitor plague, identifizierte Hersteller (~identified vendors)", "Stolen formula for capacitors causing computers to burn out", "A. Albertsen, Electrolytic Capacitor Lifetime Estimation", "Aluminium electrolytic capacitors - Principles | ELNA", "The Reaction between Anodic Aluminium Oxide and Water", https://en.wikipedia.org/w/index.php?title=Capacitor_plague&oldid=993661557, Wikipedia articles needing page number citations from November 2015, Articles needing additional references from August 2018, All articles needing additional references, Articles with unsourced statements from November 2015, Creative Commons Attribution-ShareAlike License, capacitance value decreases to below the rated value, increased capacitance value, up to twice the rated value, which fluctuates after heating and cooling of the capacitor body, Bulging of the vent on top of the capacitor. [15] However, the company would not reveal the name of the capacitor maker that supplied the faulty products. Many of the poorly designed capacitors made it to mass market. All electrolytic capacitors with non-solid electrolyte age over time, due to evaporation of the electrolyte. Many PC users were affected, and caused an avalanche of reports and comments on thousands of blogs and other web communities. This oxide layer is electrically insulating and serves as the dielectric of the capacitor. Many other equipment manufacturers unknowingly assembled and sold boards with faulty capacitors, and as a result the effect of the capacitor plague could be seen in all kinds of devices worldwide. [17], The non-solid aluminium electrolytic capacitors with improperly formulated electrolyte mostly belonged to the so-called "low equivalent series resistance (ESR)", "low impedance", or "high ripple current" e-cap series. It was only the electrolytics that were failing. If the energy is extremely high, however, a complete failure can occur. Inorganic Chemistry. After roughly 120 years of development billions of these inexpensive and reliable capacitors are used in electronic devices. A materials scientist working for Rubycon in Japan left the company, taking the secret water-based electrolyte formula for Rubycon's ZA and ZL series capacitors[citation needed], and began working for a Chinese company. Fluid leaking 5. Capacitor Failure Modes Experience has shown that capacitor failures are second only to semiconductors and vacuum tubes in components prone to malfunction in electronic equipment. [37] The first commercially used electrolytes in the mid-twentieth century were mixtures of ethylene glycol and boric acid. Aluminium electrolytic capacitors with non-solid electrolyte are generally called "electrolytic capacitors" or "e-caps". Unhappily this layer of electrolyte has electrical resistance which, along with the (negligible) resistance of the connecting leads and alumin(i)um foil plates, forms the capacitor’s Equivalent Series Resistance. The failure of electrolytic capacitors can be hazardous, resulting in an explosion or fire. The liquid electrolyte, which is the cathode of the capacitor, covers the irregular surface of the oxide layer of the anode perfectly, and makes the increased anode surface effectual, thus increasing the effective capacitance. [38][page needed] The initial self-healing process for building a new oxide layer is prevented by a defect or a weak dielectric point, and generated hydrogen gas escapes into the capacitor. If a run capacitor fails, the motor can display a variety of problems including not starting, overheating, and vibrating. For aluminum polymers, ESR impedance increases due to polymer degradation. I thought this is an electrolytic capacitor and it should have the weak-point; in order to avoid them building up too much pressure during a failure. To avoid this, film/foil capacitors with infinite dU/dT, or complex series construction metallized capacitors with high dU/dT, should be used in high-current applications. BTW, he is really funny and if you want to hear a rant on Electrolytic s then you need to watch that video. almost anhydrous electrolytes based on organic solvents, such as. I also found this initially but mention it here only in passing as it applied to other types of Capacitors and I thus far all I am seeing fail are electrolytic. An air conditioner that doesn’t blow cold air is one of the first signs of a problem many homeowners notice. I imagine the post is oriented towards electrolytic capacitors, but I’ll give a quick run down of the types you’re likely to see in consumer electronics. As it is known that aluminium can be dissolved by alkaline liquids, but not that which is mildly acidic, an energy dispersive X-ray spectroscopy (EDX or EDS) fingerprint analysis of the electrolyte of the faulty capacitors was made, which detected dissolved aluminium in the electrolyte. In the same year, the scientist's staff left China, stealing again the mis-copied formula and moving to Taiwan, where they would have created their own company, producing capacitors and propagating even more of this faulty formula of capacitor electrolytes. Reverse voltage will also damage a tantalum, as will extreme thermal shock from out-of-control mounting profiles or heating from excess ripple current. Thus, even in the first apparently water-free electrolytes, esterification reactions could generate a water content of up to 20 percent. Asymmetrical or stretched plastic jacket 4. Bob Parker, www.ludens.cl, and wikipedia.org do a much better job of explaining this than I and have built special circuitry to identify these out of spec capacitors. Next step is to purchase a ESR meter. Electrolytic capacitors that operate at a lower temperature can have a considerably longer lifespan. The normal process of oxide formation or self-healing is carried out in two reaction steps. But it is also a chemical mixture of solvents with acid or alkali additives,[26] which must be non-corrosive (chemically inert) so that the capacitor, whose inner components are made of aluminium, remains stable over its expected lifetime. In 2001, a scientist working in the Rubycon Corporation in Japan stole a mis-copied formula for capacitors' electrolytes. [14], In the November/December 2002 issue of Passive Component Industry, following its initial story about defective electrolyte, reported that some large Taiwanese manufacturers of electrolytic capacitors were denying responsibility for defective products.[15]. McGraw-Hill. The results of chemical analysis were confirmed by measuring electrical capacitance and leakage current in a long-term test lasting 56 days. These electrolytic capacitors are typically labeled "low-impedance", "low-ESR", or "high-ripple-current" with voltage ratings up to 100 V. Despite these advantages, researchers faced several challenges during development of water-based electrolytic capacitors. I think, I am going to with the kit from Bob Parker at http://members.ozemail.com.au/~bobpar/esrmeter.htm. In addition to the good conductivity of operating electrolytes, there are other requirements, including chemical stability, chemical compatibility with aluminium, and low cost. The normal lifespan of a non-solid electrolytic capacitor of consumer quality, typically rated at 2000 h/85 °C and operating at 40 °C, is roughly 6 years. However, one independent laboratory analysis of defective capacitors has shown that many of the premature failures appear to be associated with high water content and missing inhibitors in the electrolyte, as described below. An electrolytic capacitor can fail gradually over a period of years as it dries out. The more I started looking at things that had failed around here, the more I began to see their point. Electrolytic capacitors also have a self-healing ability, although to a lesser extent than film capacitors. In any design, it is important to know how a capacitor will react to a surge or high temperatures to determine the most suitable component for the application. The capacitance usually decreases and the ESR usually increases. BLOG POST: https://tehnoblog.org/graphics-card-repair-how-i-fixed-gpu-card/ Dying GPU? ? A second aluminium foil strip, called the "cathode foil", serves to make electrical contact with the electrolyte. Patnaik, P. (2002). On air-handling equipment, the motor may start but will always fall short of normal operating speed. It is known that the "normal" course of building a stable aluminium oxide layer by the transformation of aluminium, through the intermediate step of aluminium hydroxide, can be interrupted by an excessively alkaline or basic electrolyte. Failure depends upon the capacitor type and enviroment (primarily voltage, heat and amount of ripple current). [43] Since phosphate ions were missing and the electrolyte was also alkaline in the investigated Taiwanese electrolytes, the capacitor evidently lacked any protection against water damage, and the formation of more-stable alumina oxides was inhibited. Although the analysis methods were very sensitive in detecting such pressure-relieving compounds, no traces of such agents were found within the failed capacitors. [31][32] Inhibitors—such as chromates, phosphates, silicates, nitrates, fluorides, benzoates, soluble oils, and certain other chemicals—can reduce the anodic and cathodic corrosion reactions. In e-caps using an alkaline electrolyte this aluminium hydroxide will not be transformed into the desired stable form of aluminium oxide. [16] The marks were not easily linked to familiar companies or product brands. Siegmund, Bell System Technical Journal, v8, 1. Good comparable Japanese capacitors had an electrolyte that was acidic, with a pH of around 4. Auflage. The circuit required a very high voltage capacitor and so it used two 4.7uF 400V electrolytic capacitors in series, I replaced them with one 2.2uF 900V film capacitor. [1] Shortly thereafter, two mainstream electronics journals reported the discovery of widespread prematurely failing capacitors, from Taiwanese manufacturers, in motherboards. I found that interesting because if I fail to see any hard visual evidence then I am going to be looking at the caps that are closer to high temperature locations on the circuit board. He mentioned something about his Bob Parkers ESR (Equivalent Series Resistance) meter and a google search opened up the flood gates about failing electrolytic caps and loads of information. Problems with Windows booting up? The spacer separates the foil strips to avoid direct metallic contact which would produce a short circuit. These electrolytes had a voltage-dependent life span, because at higher voltages the leakage current based on the aggressiveness of the water would increase exponentially; and the associated increased consumption of electrolyte would lead to a faster drying out. A radiation shield between the cap and the hot component prevents the hot component from accelerating failure mechanisms, which can be simply a shorter lifetime (or faster parameter drift), or the opening of the pressure relief vent in extreme cases. For electrolytic and double-layer capacitors, there will be impedance and ESR increase due to electrolyte loss. There are also a number of symptoms that will tell you if the capacitor on a motor is faulty: The motor will not start its load, but if you spin the load by hand, the motor will run properly. 41–63, A. Güntherschulze, H. Betz, Elektrolytkondensatoren, Verlag Herbert Cram, Berlin, 2. Handbook of Inorganic Chemicals. Film capacitors will have some oxidation of the metal conductors, increasing the dissipation factor. The foil is roughened by electrochemical etching to enlarge the effective capacitive surface. On a circuit board, capacitors should not be mounted close to heat sources. Dry e-caps are therefore electrically useless. The highly competitive market in digital data technology and high-efficiency power supplies rapidly adopted these new components because of their improved performance. Forming creates a very thin oxide barrier layer on the anode surface. The motherboard manufacturer ABIT Computer Corp. was the only affected manufacturer that publicly admitted to defective capacitors obtained from Taiwan capacitor makers being used in its products. A common failure mode in this application occurs when such a capacitor "leaks" dc, which upsets the operating point of the next stage. Cross-section side view of etched 10 V low voltage anode foil, SEM image of the rough anode surface of an unused electrolytic capacitor, showing the openings of pores in the anode, Ultra-thin-cross-section of an etched pore in a low-voltage anode foil, 100,000-fold magnification, light grey: aluminium, dark grey: amorphous aluminium oxide, light: pore, in which the electrolyte is active. -- I should state that I bought these from a Chinese website, so I'm not sure about the quality. High currents can cause this failure by evaporating the connection between the metallization and the end contact. Industrial espionage was implicated in the capacitor plague, in connection with the theft of an electrolyte formula. W. J. Bernard, J. J. Randall Jr., The Reaction between Anodic Aluminium Oxide and Water. Split vents Symptoms of defective capacitors may include: 1. But if capacitors are properly selected, they are also the least common.Often the useful life of capacitors is longer than the application itself. The capacitance usually decreases and the ESR usually increases. One of the aluminium foil strips, called the anode, chemically roughened and oxidized in a process called forming, holds a very thin oxide layer on its surface as an electrical insulator serving as the dielectric of the capacitor. However, the corrosion problems linked to water hindered, up to that time, the use of it in amounts larger than 20% of the electrolyte, the water-driven corrosion using the above-mentioned electrolytes being kept under control with chemical inhibitors that stabilize the oxide layer.[28][29][30][31]. One problem of the forming or self-healing processes in non-solid aluminium electrolytics is that of corrosion, the electrolyte having to deliver enough oxygen to generate the oxide layer, with water, corrosive of aluminium, being the most efficient way. The first flawed capacitors linked to Taiwanese raw material problems were reported by the specialist magazine Passive Component Industry in September 2002. The capacitance should normally degrade to as low as 70% of the rated value, and the ESR increase to twice the rated value, over the normal life span of the component, before it should be considered as a "degradation failure". Capacitors for ac applications range from high-voltage oil-filled devices, such as the one shown in Figure 5.5, to low voltage, high capacitance devices of the type typically found in power… A 2003 article in The Independent claimed that the cause of the faulty capacitors was in fact due to a mis-copied formula. That is way too low to be using these caps in home appliances. Randomly occurring failures in capacitors during their use are the most important source of failures in capacitors. However, reactions do not come to a standstill, as more and more hydroxide grows in the pores of the anode foil, and the first reaction step produces more and more hydrogen gas in the can, increasing the pressure. Because not all manufacturers had offered recalls or repairs, do-it-yourself repair instructions were written and published on the Internet. But water will react quite aggressively and even violently with unprotected aluminium, converting metallic aluminium (Al) into aluminium hydroxide (Al(OH)3), via a highly exothermic reaction that gives off heat, causing gas expansion that can lead to an explosion of the capacitor. In 2005, Dell spent some US$420 million replacing motherboards outright and on the logistics of determining whether a system was in need of replacement.[12][13]. There is no wear-out mechanism for solid aluminum or tantalum capacitors, which is a major advantage over wet aluminum capacitors. In the 1990s a third class of electrolytes was developed by Japanese researchers. During a wear-out period, failures increase per hour and become more predictable. While industrial customers confirmed the failures, they were not able to trace the source of the faulty components. Later, electrolytes were developed to work with water of up to 70% by weight. W. BONOMO, G. HOOPER, D. RICHARDSON, D. ROBERTS, and TH. But if capacitors are properly selected, they are also the least common.Often the useful life of capacitors is longer than the application itself. January 1229, pp. AC Capacitor: Reasons and Signs Associated with Failure and Defects | Insight from Your Trusted St. Paul, MN Heating and AC Repair Service Provider 8/17/2020. Broken or cracked vent, often accompanied with visible crusty rust-like brown or red dried electrolyte deposits. To avoid failures in high-temperature applications, the designer should use capacitors with lower losses, a larger size, or a higher temperature rating. Water, with its high permittivity of ε = 81, is a powerful solvent for electrolytes, and possesses high solubility for conductivity-enhancing concentrations of salt ions, resulting in significantly improved conductivity compared to electrolytes with organic solvents like GBL. When this failure occurs and a capacitor feeds a pot, the presence of dc will cause the pot to scratch when adjusted, and the pot … But even if the electrical parameters are out of their specifications, the assignment of failure to the electrolyte problem is not a certainty. Ch. The assembly is inserted into an aluminium can and sealed with a plug. This provides a reservoir of electrolyte to extend the lifetime of the capacitor. This page was last edited on 11 December 2020, at 20:21. E-caps can fail without any visible symptoms. [35] It is known that water is extremely corrosive to pure aluminium and introduces chemical defects. I also found this great article when researching ESR titled, “Capacitor Testing, Safe Discharging and Other Related Information”. Many single-phase compressors require a start capacitor to assist in starting the motor. Strange, Carts USA 2006, The Effects of Electrolyte Composition on the Deformation Characteristics of Wet Aluminium ICD Capacitors, J. M. Sanz, J. M. Albella, J. M. Martinez-Duart, On the inhibition of the reaction between anodic aluminium oxide and water. The report of Hillman and Helmold proved that the cause of the failed capacitors was a faulty electrolyte mixture used by the Taiwanese manufacturers, which lacked the necessary chemical ingredients to ensure the correct pH of the electrolyte over time, for long-term stability of the electrolytic capacitors. However, if inhibitors are used in an insufficient amount, they tend to increase pitting. Because it has been customary in electrolytic capacitors to bind the excess hydrogen by using reducing or depolarizing compounds, such as aromatic nitrogen compounds or amines, to relieve the resulting pressure, the researchers then searched for compounds of this type. The name "electrolytic capacitor" derives from the electrolyte, the conductive liquid inside the capacitor. At the beginning of the 1990s, some Japanese manufacturers started the development of a new, low-ohmic water-based class of electrolytes. Electrolytics are the largest capacitors in the radio, with values from about 5 mfd (microfarads) to as much as 80 or even 200 mfd. The improved conductivity of the new electrolyte can be seen by comparing two capacitors, both of which have a nominal capacitance of 1000 μF at 16 V rated voltage, in a package with a diameter of 10 mm and a height of 20 mm. This completes the ‘outer’ electrical connection to the alumin(i)um oxide dielectric, which coats the anode foil. Ceramics will have capacitance loss due to oxide vacancy migration. They always show low capacitance values and very high ohmic ESR values. Up to the mid 1990s electrolytes could be roughly placed into two main groups: It was known that water is a very good solvent for low ohmic electrolytes. [34] However, the pH value of the electrolyte is ideally about 7 (neutral); and measurements carried out as early as the 1970s have shown that leakage current is increased, due to chemically induced defects, when the pH value deviates from this ideal value. Its a difficult and time consuming process when they don’t show obvious signs of bulging or leaking as the photo above shows. [citation needed] After several years of development, researchers led by Shigeru Uzawa had found a mixture of inhibitors that suppressed the aluminium hydration.