JPS5923883A - Oxide scale inhibitor - Google Patents

Abstract

PURPOSE:To provide an oxide scale inhibitor which has high coating efficiency and picklability and is suited for hot rolled steel sheets, by combining carbonates and hydroxides of alkaline earth metals and saccharides. CONSTITUTION:A scale inhibitor consists of an aq. soln. contg. 0.1-20wt% >=1 kinds among carbonates and hydroxides of alkaline earth metals and 0.1- 20wt% >=1 kinds among saccharides. The carbonate of alkaline earth metals, for example, CaCO3 is decomposed to CaO and CO2 at high temp.; CaO suppresses the transformation of FeO to Fe3O4 and alphaFe at <=560 deg.C, and forms the scale contg. rich FeO, thereby improving picklability. The saccharides improve the coating efficiency of CaCO3 on the surface of steel strips and is carbonized at high temp., thereby forming a carbide film on the scale surface. As a result, the intrusion of O from the inside of the atmosphere into the scale is prevented and the growth of scale is thus presumably inhibited.

Description

【発明の詳細な説明】 本発明は熱間圧延銅帯の表面に生成する酸化スケールの
抑制剤Ｃ１関し、特に熱間圧延仕上スタンドと巻取機間
（−おける表面温度が、５００〜！ｌ　（ｌ　ＯＣと云
った高温状態の熱間圧延鋼帯に生成する酸化スケールを
抑制する用途に好適な酸化スケール抑制剤にががるもの
である。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inhibitor C1 for oxide scale generated on the surface of a hot rolled copper strip, particularly when the surface temperature between the hot rolling finishing stand and the winding machine (-) is 500~!L. This article describes an oxidation scale inhibitor suitable for suppressing oxidation scale generated on hot-rolled steel strip under high temperature conditions, such as OC.

さ−Ｃ周知の通り熱間圧延鋼帯表面には酸化スケールが
生成しているため、次工程特に冷間圧延に使用する際は
、塩酸もしくは硫酸酸洗して酸化スケールを除去するが
、該酸洗はがなりの長時間を必要とし、かっ酸洗によっ
て失なわれる鋼量も多く、経済的に改善すべき問題が多
い。As is well known, oxidized scale forms on the surface of hot rolled steel strips, so when used in the next process, especially cold rolling, the oxidized scales are removed by pickling with hydrochloric acid or sulfuric acid. Pickling requires a long period of time, and a large amount of steel is lost during pickling, so there are many problems that need to be improved economically.

そこで従来、前記酸化スケールの生成を防止もしくは減
少させるため、Ｃｒ２Ｏ２，８１０２等の無機物を主体
とするスケール抑制剤が用いられていた。（特開昭４９
−６３６１１号公報）またスケール抑制効果を高めるた
め、塗布すべき場所や塗布手段にも工夫が行なわれ、た
とえば特開昭５３−３７５３９号公報に↑６いて開示さ
れたように、熱間仕上スタンドと巻取機間に〕ｔＧいて
、アルカリ土類金属の酸化物、炭酸塩、水酸化物或はそ
の能様々の薬剤を塗布するが、またはこれら塩類の水溶
液を噴射、伺着させて酸洗処理を軽減する手段が提示さ
れている。Therefore, in order to prevent or reduce the formation of the oxide scale, scale inhibitors mainly composed of inorganic substances such as Cr2O2, 8102 have been used. (Unexamined Japanese Patent Publication No. 1973
(No. 63611) Furthermore, in order to improve the scale suppression effect, improvements have been made to the areas where the coating should be applied and the coating methods. Between the winder and the winding machine, alkaline earth metal oxides, carbonates, hydroxides, or various agents thereof are applied, or an aqueous solution of these salts is sprayed and deposited for pickling. A means to reduce processing is presented.

周知の如く、高配の酸化性雰囲気中に４，５いて鋼表面
が酸化し、そのスケールが成長する現象は、その鋼、酸
化物界面から酸化物側に鉄イオンが拡散し、他方酸化物
表面力・ら酸化物内部−＼酸素イオンが拡散する過程に
より進イ了する。即ち鋼の酸化には鉄イオン、酸素イオ
ンの挙動、酸化物層内の格子構造の条件が第−量的に関
係し、更に酸化物層の金属面からの剥離、亀裂発生など
が酸化速度に２次的な影響をもつ。As is well known, the phenomenon in which the steel surface oxidizes and scale grows in a highly oxidizing atmosphere is that iron ions diffuse from the steel-oxide interface to the oxide side, and on the other hand, the oxide surface The inside of the oxide is completed by the process of diffusion of oxygen ions. In other words, the behavior of iron ions and oxygen ions, and the conditions of the lattice structure within the oxide layer are quantitatively related to the oxidation of steel, and the oxidation rate is also affected by the peeling of the oxide layer from the metal surface, the occurrence of cracks, etc. It has secondary effects.

ろパ さくうに、高温環境におり・て酸化物の融解妾起ると酸
化が著しく促進され、また鉄を５６０Ｃ以北の高温で酸
化するとＦｅｄ、　　Ｆｅ３Ｏ４＋　Ｆｅ２Ｏ３等のス
ケールが生成し、酸洗性の良いＦｅｄ（ウスタイト）は
、５６０Ｃ以下ではＦｅと酸洗性の悪いＦｃ３０４（マ
グネタイト）とに共析分解することが知られている。In contrast, oxidation is significantly accelerated when oxides melt in a high-temperature environment, and when iron is oxidized at high temperatures north of 560C, scales such as Fed, Fe3O4+ Fe2O3, etc. are generated, and pickling properties are reduced. It is known that Fed (wustite), which has good properties, decomposes eutectoidally into Fe and Fc304 (magnetite), which has poor pickling properties, at temperatures below 560C.

以上の知見から本発明者等はＦｅＯ（ウスタイト）の変
態によって生成するＦｅ３Ｏ４（マグネタイト）の生成
量を低減すること、酸化物内部への酸素イオン拡散を阻
止して、酸化スケールの成長を防止すること、およびＣ
ａＣＯ３のＦｅＯ変態を制御する事実から、ＣａＣ０３
の付着効率を高めることを目的として、種々検討した結
果、意外にもアルカリ土類金属の炭酸塩、水酸化物と糖
類の組合せが、」１記目的を達成することが即ち本発明
は、アルカリ土類金属の炭酸塩、水酸化物の１種もしく
は２種以」二を０１〜２０ｗｊ％含有すると共に、それ
に加えて糖類の１種もしくは２種以上を０．　］〜２０
ｗｔ％含有する水溶液からなることを特徴とする熱間圧
延鋼帯の酸化スケール抑制剤を提供するものである。Based on the above findings, the inventors of the present invention have developed a method to reduce the amount of Fe3O4 (magnetite) produced by the transformation of FeO (wustite), to prevent oxygen ion diffusion into the oxide, and to prevent the growth of oxide scale. That, and C
From the fact that it controls the FeO transformation of aCO3, CaC03
As a result of various studies with the aim of increasing the adhesion efficiency of Contains 0.1 to 20 wj% of one or more of earth metal carbonates and hydroxides, and in addition, contains 0.01 to 20 wj% of one or more of saccharides. ]~20
The present invention provides an oxidation scale inhibitor for hot rolled steel strip, characterized in that it consists of an aqueous solution containing wt%.

アルカリ土類金属の炭酸塩、水酸化物の中、ＣａＣＯ３
ｆ例にとればＣａＣＯ３は高温（８２５Ｃ）ＦｅＯの濃
化したスケールとなり、酸洗性を向上させる。また糖類
はＣａＣｏ３の鋼帯表面への塗布効率を上げ、かつ高温
において炭化し、スケール表面上に炭化被膜を形成する
。その結果雰囲気（空気）中からスケール内部への０の
侵入を阻止して、スケールの成長を抑制するものと推定
される。Among alkaline earth metal carbonates and hydroxides, CaCO3
In example f, CaCO3 becomes a concentrated scale of high temperature (825C) FeO, which improves pickling properties. In addition, saccharides increase the coating efficiency of CaCo3 on the steel strip surface, and are carbonized at high temperatures to form a carbonized film on the scale surface. As a result, it is presumed that the intrusion of 0 from the atmosphere (air) into the interior of the scale is prevented, thereby suppressing the growth of the scale.

本発明に使用されるアルカリ土類金属の炭酸塩、硝酸塩
水酸化物の具体例は、炭酸マグネシウム、炭酸力ルンウ
ム、硝酸マグネシウム、硝酸カルシウム、水酸化マグネ
シウム、水酸化カルシウムであり、特に炭酸カルシウム
が好適に使用される。また添加される量的範囲は、水に
対して０．１〜２０　ｗｔ％の範囲であって、ここで０
１係以下ではスケールの改質効果がなく、また２０％以
上では、塗布する際のノズルつまりＷの作業上支障金き
たす。Specific examples of alkaline earth metal carbonates and nitrate hydroxides used in the present invention are magnesium carbonate, carbonate, magnesium nitrate, calcium nitrate, magnesium hydroxide, and calcium hydroxide. Preferably used. The quantitative range of addition is 0.1 to 20 wt% based on water, where 0.
If it is less than 1%, there is no effect of modifying the scale, and if it is more than 20%, it will cause problems in the operation of the nozzle, that is, W during coating.

さらに上記化合物と組合せて使用される糖類はザツカロ
ーズ、ブドウ糖、果糖、麦芽糖、乳糖等の甘味料、水ア
メ、粉アメ、異性化糖等のでんぷん糖およびマルチトー
ル等の糖アルコール、さらに精製糖の廃液である糖密か
使用され、添加する量は０．１〜２０ｗｔ％であって、
０．１％以下ではスケール成長抑制に効果がなく、また
２０係以」二添力１１シても効果の増加は期待できない
。Furthermore, sugars used in combination with the above compounds include sweeteners such as zatzkarose, glucose, fructose, maltose, and lactose, starch sugars such as starch syrup, powdered candy, and high-fructose sugar, and sugar alcohols such as maltitol, as well as refined sugars. The waste liquid molasses is used, and the amount added is 0.1 to 20 wt%,
If it is less than 0.1%, it will not be effective in suppressing scale growth, and even if the additive force is 11% or more than 20%, no increase in the effect can be expected.

次Ｃ二実が０例を・あげて本発明全具体的に説明する。Next, the present invention will be explained in detail by giving two examples.

実施例 炭素含量０．０５％の熱間圧延板を塩酸々洗、水洗、脱
水乾燥した７　５　Ｘ　５　Ｑ　ｍｍの試片を、９００
Ｃｔ１加熱炉で加熱し、次いで加熱炉から取り出し、試
片温１ｉ９００〜６００”Ｃの温度において、下記第１
表に示すスケール抑制剤を、吐出圧：３　ｋｆｌ、／　
ｃａ、流策４１／＃Ｉの条件下で塗布し、５０　’Ｃ／
　Ｉ＋ｒの冷却速度で常温まで冷却した。Example A hot rolled plate with a carbon content of 0.05% was washed with salt and water, washed with water, and dehydrated and dried.
Heated in a Ct1 heating furnace, then removed from the heating furnace, and heated at a specimen temperature of 1i900 to 600"C.
Discharge pressure: 3 kfl, /
ca, applied under flow rate 41/#I conditions, 50'C/
It was cooled to room temperature at a cooling rate of I+r.

該試片を顕微鏡で、スケール１ｑさをＸ線回析でスケー
ル組成を調べた後、１５％硫酸液侃１８０Ｃで酸洗し、
時間を測定した。その１％１１．未全第１表に示す。After examining the scale composition of the sample using a microscope and using X-ray diffraction for 1 q of scale, pickling with 15% sulfuric acid solution at 180C.
The time was measured. That 1%11. It is shown in Table 1, which is incomplete.

以上の結果より本発明の酸化スケール抑制剤は糖類を含
有するため、ＣａＣＯ３を水に分散した比較例よりＣａ
Ｏ付着量が多く、すなわらＣ，ＩＣ０１の塗布効率が高
く、酸洗性が優れ、また無塗布の比較例（二対して犬ｒ
ｊｊな酸洗性の向」−が見られ、本発明抑ｆｆｆｌＪ剤
の有用性が分る。From the above results, since the oxidation scale inhibitor of the present invention contains saccharides, Ca
The amount of O deposited is large, that is, the coating efficiency of C and IC01 is high, and the pickling property is excellent.
A strong pickling property was observed, demonstrating the usefulness of the inhibitor of the present invention.

Claims (1)

【特許請求の範囲】[Claims] アルカリ土類金属の炭酸塩、水酸化物の１種もしくは２
種以上を０１〜２０　ｗｔ　％含有すると共に、それに
加えて糖類の１種もしくは２種以上ｆＱ。］〜２０　ｗ
ｔ％含有する水溶液からなることを特命とする熱間圧延
鋼帯の酸化スケール抑制剤。One or two types of alkaline earth metal carbonates and hydroxides
fQ containing 01 to 20 wt % of at least one type of saccharide and, in addition, one or more types of saccharide. ]~20w
An oxidation scale inhibitor for hot rolled steel strips specially made of an aqueous solution containing t%.