The steel in addition to iron, carbon and join the other elements called alloy steel. Main alloy elements are including manganese, silicon, rare earth, chromium and so on. In particular, all kinds of alloy elements in total amounts under half (almost 50%) by weight are improving its mechanical properties. In other words, alloy steel is metal materials that in order to get or improve steel some performance therefore adds one or many kinds of alloy element content of provisions limit value (GB/T 13304) in steel. According to add distinction elements and take the appropriate processing process, a high strength, high toughness, wear resistance, corrosion resistance, low temperature resistance, high temperature resistant, nonmagnetic and other special performance alloy steel can be gained. Alloy steel can divide into a variety of types, usually in the alloy element content divided into low alloy steel (< 5%) content, medium alloy steel (content 5% ~ 10%) and high alloy steel (content > 10%); In accordance with the quality fell into high quality alloy steel, trait alloy steel; According to the characteristic and purpose and can be separated into bearing steel and special performance steel (such as soft magnetic steel, permanent magnetic steel, no magnetic steel).
(2) Stainless steel:
Stainless steel is steel that is resistance to air, steam, water, weak corrosive medium and acid, alkali, salt and chemical etching corrosion. Application in the contemporary society, the resistances to weak corrosive medium corrosion of steel is name stainless steel; whereas resistance to chemical medium corrosion of steel is name acid-resistant steel. Moreover, stainless steel has another name inox steel in the metallurgy field. Stainless steel corrosion resistance depends on the contained alloy element in the steel. These alloy elements are including nickel, molybdenum, titanium, nitrogen and so on, adding some alloy elements aim to meet the various stainless steel organizations and performance requirements. However, the main stainless steel alloy element is chromium, only when the chromium content reaches a certain value (at least 10.5%), then steel have corrosion resistance. Due to stainless steel has tremendous resistance corrosion, therefore it can make engineering structure component permanently keeping integrity. In particular, chromium stainless steel is not only retaining mechanical strength, but also maintaining high extensibility, which are satisfied with architect and engineer. It means that stainless steel is prevalent in the community. Furthermore, stainless steel represents more than 100 numbers of industry steel and has favorable performance in application area; rather than just stand for one specific stainless steel.
(3)PH:
The full name of PH is hydrogen ion concentration. P stands for concentration and H is hydrogen ion. In other words, PH actually is one method that measure PH value in the aqueous solutions. The measurement formula is
. \mathrm{pH} = - \log_{10}(a_{\textrm{H}^+}) = \log_{10}\left(\frac{1}{a_{\textrm{H}^+}}\right). The application scope of PH is between 0-14. To be specific, when PH=7, it means that water is neutral; when PH<7, water is acidic and if the value is smaller, the acid will stronger; when PH>7, water is alkaline and if the value bigger, the alkaline will stronger. Due to solutions are not the pure, so merely using hydrogen ion concentration measure PH value is inaccurate, hence using measure hydrogen activity method would be reasonable, that is pH=-lg aH+=-lgγ·cH+。In addition, a multitude of ways can be used to measure PH value. Initially, adding PH indicator in the test solutions, according to the color's change can confirm range of PH values. Secondly, using PH test paper, more detail process is that using glass rod dip a bit of test solution to test paper, then according to the test paper color change and compare the color card can achieve PH values in the solution. Lastly, using PH meter, PH meter is one of the devices to measure PH value in the solution.
(4)Anode:
Anode is oxidation reaction of electrode, that loss of electrons is oxidation or anode oxidation .However, in electricity and chemistry area, positive electrode and anode are different in concept and principal. To be more specific, positive electrode expresses high potential electrode; nevertheless, the anode is where oxidation reaction occurs. In order to make clearly, a discharging battery or galvanic cell can be analyzed. For example, current and electrode flow orientation can ensure randomly. Right is electron flows inside and current flow out direction, left is electron flows out and current flow in orientation. According to lose electricity is oxidized and the flow outside of electricity is positive electrode (high potential) principles, therefore right is positive electrode and left is anode. From those analyses, when the discharge the anode equal to the negative electrode; on the other hand, when the charge the anode equal to the positive electrode, this is the common rule in the battery field. That is to say, anode and electrode positive or negative has no inevitable relation. Furthermore, metal or metal alloy regard as anode and at the same time use electrolysis measurement to form oxide film. Those metal oxide film transform surface performance and status therefore improving resistance corrosion.
(5) Cathode:
Cathode is reduction reaction of electrode, by that means reduction is gain of electrons or cathode reduction. Likewise, in the electricity and chemistry area, negative electrode and cathode have distinction concept and principal. To be more specific, negative electrode indicate low potential electrode; whereas, the cathode is where reduction reaction occurs. Then, a discharging battery or galvanic cell can be analyzed. Obtaining electricity is reduction and the flow inside of electricity is negative electrode (low potential). In the discharge barratry, cathode is positive electrode (high potential), the electricity direction is from positive to negative. In contrast, the electron flows from negative to positive. In addition, in the electrolytic cell, cathode connects with power source's negative electrode. Next, in the cathode take place reduction reaction that is positive ion in the solution. If the solution has a variety of positive ion, in this situation the inactivity metal positive ion would be more chance to conduct reduction reaction. In particular, in the aqueous solution, before aluminum metal positive ion is impossible processing reduction reaction. What is more, in the galvanic cell, cathode is positive electron. The positive ion in the solution lean to positive electron, on the contrary, the negative ion lean to negative electron.
