建材工业窑炉用直接结合镁铬砖

1范围

  本标准规定了建材工业窑炉用直接结合镁铬砖的术语和定义、分类、形状和尺寸、技术要求、试验方法、检验规则以及包装、标志、运输、贮存和质量证明书等。本标准适用于水泥窑和玻璃窑用直接结合镁铬砖。

2规范性引用文件

  下列文件对于本文件的应用是必不可少的。凡是注日期的引用文件,仅注日期的版本适用于本文件。

  凡是不注日期的引用文件，其最新版本(包括所有的修改单)适用于本文件。

  GB/T 2992.1通用耐火砖形状尺寸 第1部分:通用砖

  GB/T 2997致密定形耐火制品 体积密度、显气孔率和真气孔率试验方法

  GB/T 3002耐火材料 高温抗折强度试验方法

  GB/T 5070含铬耐火材料化学分析方法

  GB/T 5072耐火材料 常温耐压强度试验方法

  GB/T 7320耐火制品热膨胀试验方法

  GB/T 7321定形耐火制品试样制备方法

  GB/T 10326定形耐火制品尺寸、外观及断面的检查方法

  GB/T 16546定形耐火制品包装、标志、运输和储存

  GB/T 17912回转窑用耐火砖形状尺寸

  GB/T 18930耐火材料术语

  GB/T 21114耐火材料 X射线荧光光谱化学分析 铸玻璃片法

  YB/T 370 耐火制品荷重软化温度试验方法(非示差-升温法)

  YB/T 376.1耐火制品抗热震性试验方法(水急冷法)

  YB/T 376.2 耐火制品抗热震性试验方法(空气急冷法)

3术语和定义

  GB/T 18930界定的以及下列术语和定义适用于本文件。

  直接结合镁铬砖direct bonded magnesia-chrome bricks

  是指以高纯度镁砂和铬精矿为主要原料，在1700C以上的温度下烧成的、其耐火物晶粒之间多为直接接触的制品。

4分类、形状和尺寸

4.1制品按用途分为水泥窑用直接结合镁备砖和玻璃密用直接结合镁铬砖，水泥窑用直接结合镁铬砖按Cr₂O₃,含量将其分为低路型和中铬型两个牌号，玻璃窑用直接结合镁铬砖为高路型牌号(DMC-12)。

4.2制品按外形分为直形砖和筒型砖，直形砖的形状尺寸应符合GB/T 2992.1的规定。简形砖及其他特殊形状尺寸要求由供需双方商定。

4.3水泥窑用直接结合镁砖的形状尺寸应符合GB/T 2992.1和GB/T 17912的规定，特殊要求由供需双方商定。

5技术要求

5.1直接结合镁铬砖的理化性能指标应符合表1和表2的规定。

表1水泥窑用直接结合镁铬砖的理化性能指标
项目				指标
				中铬型	低铬型
化学成分	MgO/%		μ0	≥73	≥80
	Cr2O3,/%		μ0	7~10	2~5
	SiO2/%		μ0	≤1.8
			σ	0.2
物理性能	显气孔率/%		μ0	≤18
			σ	1.0
	常温耐压强度/MPa		μ0	≥50	≥55
			σ	10
			Xmin	40	45
	荷重软化温度T0.6/℃		μ0	≥1650	≥1600
			σ	10
	抗热震稳定性/次	1100℃，水冷	μ0	≥5
			Xmin	≥4
		950℃，空气急冷	μ0	≥30
			Xmin	≥25
	热膨胀率/%			提供实测数据
热膨胀率的温度可由供需双方商定。

表2玻璃窑用直接结合镁铬砖的理化指标
项目			指标
			DMC-12
化学成分	MgO/%	μ0	≥70
	Cr2O3,/%	μ0	≥12
		σ	1.0
	SiO2/%	μ0	≤2.0
		σ	0.2
物理性能	体积密度/(g/cm)		≥3.0
	显气孔率/%	μ0	≤18
		σ	1.0
	常温耐压强度/MPa	μ0	≥45
		σ	10
		Xmin	35
	荷重软化温度T0.6/℃	μ0	≥1650
		σ	10
	抗热震稳定性/次1100℃，水冷	μ0	≥5
		Xmin	≥4
	热膨胀率/%		提供实测数据
	高温抗折强度/MPa1260℃x0.5 h		提供实测数据
热膨胀率的温度可由供箭双方商定。

5.2砖的尺寸允许偏差与外观应符合表3的规定

表3砖的尺寸允许偏差与外观质量 单位为毫米
项目		指标
尺寸允许偏差	尺寸≤230	±1.0
	尺寸>230	±1.5
楔形砖大小头尺寸	允许偏差	±1.0
	楔度差	1.0
扭曲度		≤0.5%
缺角		≤10允许，10<a+b+c<40,允许两处,≥40不允许
缺棱		≤25允许，25<e+f+g<50,允许两处,≥50不允许
裂纹长度	宽度<0.1	允许
	宽度0.1~0.25	≤40
	宽度>0.25	不允许
断面	宽度≤0.5	≤0.5
熔洞	直径	≤6
注1:特殊形状产品的外观质量和尺寸偏差由供需双方商定。 注2:简形砖按高度差由供需双方商定分档包装。

6试验方法

6.1制样

  按GB/T 7321的规定进行。

6.2MgO、Cr₂O₃、SiO₂的检验

  按GB/T 5070或GB/T 21114的规定进行。其中GB/T 5070为仲裁法体积密度、显气孔率的检验。

6.3按GB/T 2997的规定进行

6.4常温耐压强度的检验

  按GB/T 5072的规定进行。

6.5荷重软化温度的检验

  按YB/T 370的规定进行。

6.6抗热震性的检验

  按YB/T 376.1或者YBT 376.2的规定进行。其中YB/T 376.1为仲裁法。

6.7热膨胀率的检验

  按GB/T 7320的规定进行。

6.8尺寸偏差和外观质量的检验按GB/T 10326的规定进行。

6.9高温抗折强度的检验按 GB/T 3002 的规定进行。

7检验规则

7.1检验分类

  检验按类型分为出厂检验和型式检验。

7.1.1出厂检验

  产品出厂时，应进行出厂检验。出厂检验项目包括外观质量、尺寸偏差、化学成分、体积密度、常温耐压强度和显气孔率。

7.1.2型式检验

  型式检验项目包括第5章技术要求规定的全部项目。在下列情况下进行型式检验:

  a)生产工艺或原材料有较大改变时;

  b)正常生产时，每年至少进行两次;

  c)停产半年以上，恢复生产时;

  d)出厂检验结果与上次型式检验结果有较大差异时。

7.2组批

  制品按同样生产条件下同牌号组批，每批应不超过300t。

7.3抽样

7.3.1外观和尺寸检验抽样

  本标准给出的外观和尺寸抽样检验方案是按可接收质量限AQL制定的，见表4。如没有特别规定外观检验按AQL=4.0，尺寸检验按AQL=6.5抽样方案进行。如果对外观和尺寸有重严格要求时，外观可选择AQL=1.5，尺寸可选择AQL=4.0抽样方案，但需要在双方协议中注明。

  外观尺寸检验的样本，通常应在制造厂交付的成品垛中一次性随机抽取。为了便于抽样，制造厂交付的制品应按砖型和生产时间顺序整齐码放，并留抽样作业通道。抽样前，应先清点交付的砖型子批中单位产品的数量(N)，再按表3规定的样本量(n)抽取样品。当外观和尺寸规定的抽样数一致时，抽样总数=外观抽样数n=尺寸抽样数n,所抽样品的外观和尺寸分别检验，按各自对应的接收数Ac进行质量判定。当外观和尺寸规定的抽样数n不同时，抽样总数应按n大的数一次抽取，所抽样品的外观和尺寸全部进行检验，然后按各自对应的接收数Ac进行质量判定。

表4尺寸和外观检验抽样方案
接收质量限AQL%	批量 N块	样本量n块	接收数Ac 块
1.5	≤31	N	剔除不合格品
	32~1200	32	1
	1201~3200	50	2
	3201~10000	80	3
	>10000	125	5
4.0	≤12	N	剔除不合格品
	13~280	13	1
	281~500	20	2
	501~1200	32	3
	1201~3200	50	5
	3201~10000	80	7
	>10000	125	10
6.5	≤7	N	剔除不合格品
	8~150	8	1
	151~280	13	2
	281~500	20	3
	501~1200	32	5
	1201~3200	50	7
	3 201~10000	80	10
	>10000	125	14

7.3.2理化性能检验抽样

  样品应在成品垛上随机抽取。特殊情况时经双方协商一致也可以在生产过程中(如制品出窑时)随机抽取。样品不得有影响理化质量特性的外观缺陷。

7.4判定规则

7.4.1外观质量和尺寸偏差判定

  样品抽取后，应按产品质量标准的要求对每件样品的外观和尺寸质量分别做出“合格”或“不合格判定。所有样品检测后，分别统计外观和尺寸累计不合格样品的数量(y)，并将，与表3中规定的接收数Ac进行比较。若y≤Ac，判该子批制品合格:若y>Ac，则判该子批制品不合格。外观或尺寸检验不合格子批，如果通过检选可以剔除批中的不合格品，允许生产方检选后重新交付，再次进行验收。如果不合格子批不能通过检选提高质量，则拒收该批产品。

7.4.2理化性能的判定

  定形耐火制品理化质量特性的验收抽样检验项目包括MgO含量、Cr₂O₃;含量、SiO₂含量，体积密度、显气孔率、耐压强度、荷重软化温度和热震稳定性，其中 MgO含量、Cr₂O₃;含量、SiO₂含量、荷重软化温度的判定可按表5和表6进行(两个表样本量不同，可以任选其一)，体积密度、显气孔率、耐玉强度和热震稳定性的判定按表6进行，常温耐压强度的单值不允许低于X_min，其中σ是表1和表2中的标准偏差，S是出现检测不合格项时加测后9个样品的标准偏差，上述各项指标满足表5或者表6要求的判定为合格。

表5以批均值为质量指标的单一质量特性的合格/不合格判定(n=3)
质量要求	第一次测试1个样品		两次累计测试3个样品
	测试结果	判定	测试结果	判定
低值不适	xi≥μ0	合格	–	–
	xi<μ0	继续检验	x的平均值≥μ0	合格
			x的平均值<μ0	不合格
高值不适	xi≤μ0	合格	–	–
	xi>μ0	继续检验	x的平均值≤μ0	合格
			x的平均值>μ0	不合格

表6以批均值为质量指标的单一质量特性的合格/不合格判定(n=9)
质量要求	第一次测试3个样		两次累计测试9个样
	测试结果	判定	测试结果	判定
低值不适	x的平均值≥μ0	合格	–	–
	x的平均值<μ0-1.5σ	不合格	–	–
	μ0-1.5σ≤x的平均值<μ0	继续检验	x的平均值≥μ0-0.62S	合格
			x的平均值<μ0-0.62S	不合格
高值不适	x的平均值≤μ0	合格	–	–
	x的平均值>μ0+1.5σ	不合格	–	–
	μ0<x的平均值≤μ0+1.5σ	继续检验	x的平均值≥μ0+0.62S	合格
			x的平均值>μ0+0.62S	不合格

7.5综合判定

  检验批所有应验收的理化性能和外观质量、尺寸偏差全部合格，则该批产品合格，否则为不合格.

8包装、标志、运输、贮存和质量证明书

8.1包装

  砖的包装应该采取防潮措施。

8.2标志、运输和贮存

  按GB/T 16546进行。

8.3质量证明书

  砖出厂时应附有质量证明书，质量证明书应包括:供方名称或厂标、需方名称、生产日期、保质期、合同号、产品名称、标准编号、牌号、砖号、批号及相应的理化检验结果。

 

 

 

Direct bonded magnesium-chrome bricks for furnaces in the building materials industry

1 Range

  This standard specifies the terms and definitions, classification, shape and size, technical requirements, test methods, inspection rules, packaging, marking, transportation, storage and quality certificates of directly bonded magnesia chrome bricks for industrial kilns of building materials. This standard applies to directly bonded magnesium-chrome bricks for cement and glass kilns.

2 Normative reference documents

  The following documents are essential for the application of this document. For dated references, the date-only version applies to this document.

  For undated references, the latest version (including all amendment orders) applies to this document.

  GB/T 2992.1 Shape and dimensions of general purpose firebricks – Part 1: general purpose bricks

  Test method for bulk density, apparent porosity and true porosity of GB/T 2997 compact shaped refractory products

  GB/T 3002 refractories high temperature bending strength test method

  GB/T 5070 chromium containing refractory chemical analysis method

  GB/T 5072 refractories – normal temperature compressive strength test method

  Test method for thermal expansion of GB/T 7320 refractory products

  GB/T 7321 shaped refractory product sample preparation method

  GB/T 10326 shaped refractory products size, appearance and section inspection method

  GB/T 16546 shaped refractory products packaging, marking, transportation and storage

  GB/T 17912 refractory brick for rotary kiln shape and size

  GB/T 18930 refractory terminology

  GB/T 21114 refractories X-ray fluorescence spectrochemical analysis cast glass sheet method

  Test method for Load softening temperature of YB/T 370 refractory products (non-differential warming method)

  YB/T 376.1 Test method for thermal shock Resistance of Refractory products (water quench method)

  YB/T 376.2 Test method for Thermal shock Resistance of Refractory products (Air quench cooling method)

3 Terms and definitions

  GB/T 18930 and the following terms and definitions apply to this document.

  Direct bonded Magnesia-Chrome bricks

  Refers to high purity magnesia and chromium concentrate as the main raw materials, fired at temperatures above 1700C, the direct contact between the grain of the refractory products.

4 Classification, shape and size

4.1 Products are divided into cement kiln direct bonded magnesia brick and glass close direct bonded magnesia chrome brick, cement kiln direct bonded magnesia chrome brick is divided into low road type and medium chromium type two grades according to Cr2O3 content, glass kiln direct bonded magnesia chrome brick is high road type grade (DMC-12).

4.2 Products are divided into straight bricks and cylindrical bricks according to their appearance, and the shape and size of straight bricks shall comply with the provisions of GB/T 2992.1. The requirements for simple bricks and other special shapes and dimensions shall be agreed upon by both parties.

4.3 The shape and size of the direct bonded magnesite bricks for cement kilns shall comply with the provisions of GB/T 2992.1 and GB/T 17912, and the special requirements shall be agreed by the supply and demand parties.

5 Technical Requirements

5.1 The physical and chemical properties of directly bonded magnesium-chrome bricks shall comply with the provisions of Table 1 and Table 2.

Table 1 Physical and chemical properties of directly bonded magnesium-chrome bricks for cement kilns
Index				Item
				Medium chrome type	Low chromium type
Chemical composition	MgO/%		μ0	≥73	≥80
	Cr2O3,/%		μ0	7~10	2~5
	SiO2/%		μ0	≤1.8
			σ	0.2
Physical property	Apparent porosity/%		μ0	≤18
			σ	1.0
	Compressive strength at room temperature/MPa		μ0	≥50	≥55
			σ	10
			Xmin	40	45
	Softening temperature under loadT0.6/℃		μ0	≥1650	≥1600
			σ	10
	Thermal shock stability/time	1100℃, water-cooled	μ0	≥5
			Xmin	≥4
		950℃, the air is cold	μ0	≥30
			Xmin	≥25
	Thermal expansion rate /%			Provide measured data
The temperature of the thermal expansion rate can be agreed upon by the supply and demand parties.

Table 2 Physicochemical indexes of directly bonded magnesia-chromium bricks for glass kilns
Index			Item
			DMC-12
Chemical composition	MgO/%	μ0	≥70
	Cr2O3,/%	μ0	≥12
		σ	1.0
	SiO2/%	μ0	≤2.0
		σ	0.2
Physical property	Bulk density/(g/cm)		≥3.0
	Apparent porosity/%	μ0	≤18
		σ	1.0
	Compressive strength at room temperature/MPa	μ0	≥45
		σ	10
		Xmin	35
	Softening temperature under loadT0.6/℃	μ0	≥1650
		σ	10
	Thermal shock stability / 1100℃, water-cooled	μ0	≥5
		Xmin	≥4
	Thermal expansion rate /%		Provide measured data
	High temperature bending strength /MPa1260℃ x0.5h		Provide measured data
The temperature of the thermal expansion rate can be agreed by both sides of the supply arrow.

5.2 The permissible size deviation and appearance of the brick shall comply with the provisions of Table 3.

Table 3 The permissible size deviation of bricks and their apparent mass are measured in millimeters
Index		Item
Allowable deviation of dimension	Dimension≤230	±1.0
	Dimension>230	±1.5
Wedge brick size head size	Allowable deviation	±1.0
	Wedge difference	1.0
Tortuosity		≤0.5%
Missing corner		If the value is less than or equal to 10, 10<a+b+c<40, two values are allowed, and ≥40 is not allowed
Wane		≤25 is allowed; 25<e+f+g<50 is allowed; ≥50 is not allowed
Crack length	Breadth<0.1	Permit
	Breadth0.1~0.25	≤40
	Breadth>0.25	Not allow
Section	Breadth≤0.5	≤0.5
Molten cavern	Diameter	≤6
Note 1: The appearance quality and size deviation of special shape products shall be agreed by the supply and demand parties. Note 2: The simple brick is packaged according to the height difference agreed by the supply and demand parties.

6 Test methods

6.1 Sample Preparation

  According to GB/T 7321.

6.2 Inspection of MgO, Cr2O3 and SiO2

  According to GB/T 5070 or GB/T 21114. Wherein, GB/T 5070 is the test of volume density and apparent porosity by arbitration method.

6.3 According to GB/T 2997

6.4 Test of compressive strength at room temperature

  According to GB/T 5072.

6.5 Test of softening temperature under load

  According to YB/T 370.

6.6 Test of thermal shock resistance

  According to YB/T 376.1 or YBT 376.2. Where YB/T 376.1 is arbitration law.

6.7 Test of thermal expansion rate

  According to GB/T 7320.

6.8 The inspection of dimension deviation and appearance quality shall be carried out according to GB/T 10326.

6.9 The test of high temperature bending strength shall be carried out according to GB/T 3002.

7 Inspection Rules

7.1 Inspection Classification

The inspection is divided into factory inspection and type inspection according to the type.

7.1.1 Factory inspection

The product shall be inspected before leaving the factory. Factory inspection items include appearance quality, dimensional deviation, chemical composition, bulk density, pressure strength at room temperature and apparent porosity.

7.1.2 Type inspection

Type inspection items include all items specified in Chapter 5 Technical requirements. Type inspection is performed in the following cases:

  a) When there is a major change in the production process or raw materials;

  b) During normal production, at least twice a year;

  c) stop production for more than half a year and resume production;

  d) When there is a big difference between the factory inspection result and the last type inspection result.

7.2 Batch Group

  Products according to the same production conditions of the same brand batch, each batch should not exceed 300t.

7.3 Sampling

7.3.1 Sampling for appearance and dimension inspection

  The sampling inspection scheme of appearance and dimension given in this standard is formulated according to the acceptable quality limit AQL, see Table 4. If there is no special provision, the appearance inspection shall be carried out according to AQL=4.0, and the size inspection shall be carried out according to AQL=6.5 sampling scheme. If there are strict requirements on appearance and size, AQL=1.5 can be selected for appearance, and AQL=4.0 can be selected for size sampling scheme, but it needs to be indicated in the agreement between the two parties.

  Samples for dimensional inspection should normally be randomly selected at one time in the finished product stacks delivered by the manufacturer. In order to facilitate sampling, the products delivered by the manufacturer should be neatly placed according to the brick type and production time order, and the sampling operation channel should be left. Before sampling, the number of units of product (N) in the brick sublot delivered shall be counted and samples shall be taken according to the sample size (n) specified in Table 3. When the sampling numbers specified by the appearance and size are consistent, the total number of samples = the appearance sampling number n= the size sampling number n, the appearance and size of the samples taken are respectively inspected, and the quality is determined according to the corresponding receiving number Ac. When the appearance and size of the specified sampling number n is different, the total number of samples should be taken by n large number once, the appearance and size of the samples taken are all inspected, and then the quality is determined according to the corresponding receiving number Ac.

Table 4 Sampling scheme for dimensional and visual inspection
Receive quality limit AQL%	Batch N block	Sample size n blocks	Reception number Ac block
1.5	≤31	N	Eliminate nonconforming products
	32~1200	32	1
	1201~3200	50	2
	3201~10000	80	3
	>10000	125	5
4.0	≤12	N	Eliminate nonconforming products
	13~280	13	1
	281~500	20	2
	501~1200	32	3
	1201~3200	50	5
	3201~10000	80	7
	>10000	125	10
6.5	≤7	N	Eliminate nonconforming products
	8~150	8	1
	151~280	13	2
	281~500	20	3
	501~1200	32	5
	1201~3200	50	7
	3 201~10000	80	10
	>10000	125	14

7.3.2 Sampling for physical and chemical properties inspection

  Samples should be randomly drawn on the finished stack. In special cases, it can also be randomly extracted during the production process (such as when the product is out of the kiln) by consensus of the two parties. The sample shall not have appearance defects that affect the physical and chemical quality characteristics.

7.4 Decision Rules

7.4.1 Determination of appearance quality and size deviation

  After sample extraction, the appearance and dimensional quality of each sample should be determined as “qualified” or “unqualified” according to the requirements of the product quality standard. After all samples are tested, the number of accumulated nonconforming samples (y) of appearance and size is counted separately and compared with the number of acceptances Ac specified in Table 3. If y≤Ac, the sub-batch product qualified: if y>Ac, the sub-batch product unqualified. The appearance or size inspection of the unqualified batch, if passed the inspection can be removed from the batch of unqualified products, allowing the manufacturer to re-deliver after the inspection, again for acceptance. If the unqualified batch does not pass the inspection to improve the quality, the batch will be rejected.

7.4.2 Determination of physical and chemical properties

  The acceptance sampling inspection items of physical and chemical quality characteristics of shaped refractory products include MgO content, Cr2O3; Content, SiO2 content, bulk density, apparent porosity, compressive strength, load softening temperature and thermal shock stability, among which MgO content, Cr2O3; The determination of content, SiO2 content and load softening temperature can be carried out according to Table 5 and Table 6 (the sample size of the two tables is different, you can choose one of them). The determination of bulk density, apparent porosity, jade resistance and thermal shock stability can be carried out according to Table 6. The single value of compressive strength at room temperature is not allowed to be lower than Xmin, where σ is the standard deviation in Table 1 and Table 2. S is the standard deviation of the 9 samples after testing when there are nonconforming items. If the above indexes meet the requirements of Table 5 or Table 6, they are judged to be qualified.

Table 5 Pass/Fail determination of a single quality feature with batch average as quality index (n=3)
Quality requirement	Test 1 sample for the first time		Three samples were tested twice
	Test result	Determine	Test result	Determine
Low-value discomfort	xi≥μ0	Up to standard	–	–
	xi<μ0	Further inspection	Mean of x≥μ0	Up to standard
			Mean of x<μ0	Below standard
High value discomfort	xi≤μ0	Up to standard	–
	xi>μ0	Further inspection	Mean of x≤μ0	Up to standard
			Mean of x>μ0	Below standard

Table 6 Pass/Fail determination of a single quality feature with lot average as quality index (n=9)
Quality requirement	Test 3 samples for the first time		A total of 9 samples were tested twice
	Test result	Determine	Test result	Determine
Low-value discomfort	Mean of x≥μ0	Up to standard	–	–
	Mean of x<μ0-1.5σ	Below standard	–	一
	μ0-1.5σ≤Mean of x<μ0	Further inspection	Mean of x≥μ0-0.62S	Up to standard
			Mean of x<μ0-0.62S	Below standard
High value discomfort	Mean of x≤μ0	Up to standard	–
	Mean of x>μ0+1.5σ	Below standard	–
	μ0<Mean of x≤μ0+1.5σ	Further inspection	Mean of x≥μ0+0.62S	Up to standard
			Mean of x>μ0+0.62S	Below standard

7.5 Comprehensive Judgment

  If all the physical and chemical properties, appearance quality and dimensional deviation of the inspection batch to be accepted are qualified, the batch of products is qualified, otherwise it is unqualified.

8 Packing, marking, transportation, storage and quality certificate

8.1 Packaging

  Bricks should be packed with moisture-proof measures.

8.2 Marking, transportation and storage

  Proceed as GB/T 16546.

8.3 Quality Certificate

  The quality certificate shall include: supplier name or factory standard, demander name, production date, shelf life, contract number, product name, standard number, brand number, brick number, batch number and corresponding physical and chemical inspection results.